MECHANICAL IMPORTANT CONCEPT QUESTIONS
1. The axes of a three-cylinder air compressor are at 120° to one another and their connecting
rods are coupled to a single crank. The length of each connecting rod is 240 mm and the
stroke is 160 mm. The reciprocating parts have a mass of 2.4 kg per cylinder. What is the
maximum value of primary force if the engine runs at 1800 rpm?
2. A porter governor has a maximum and minimum speed of 200 rpm and 150 rpm
respectively. If the effective load on the sleeve is 30 kgf. The governor efforts would be
___________ kgf
3. A uniform disc of 50 kg mass, 800 mm diameter and 840 rpm rotational speed is mounted on
a shaft. The plane of the disc is not perfectly at right angles to the axis of the shaft but has an
error of 1.5 degree. The gyroscopic couple acting on the bearing is _________ Nm.
4. Each ball of a Porter governor has a mass of 6 kg and the mass of the sleeve is 40 kg. The
upper arms are 300 mm long and are pivoted in the axis of rotation where as the lower arms
are 250 mm long and are attached to the sleeve at a distance of 40 mm from axis and radius
of the governor is 150 mm. What will be the power of governor for 1% change in speed.
5. A four-cylinder in-line reciprocating engine is shown in the diagram given below. The
cylinders are numbered 1 to 4 and the firing order is 1-4-2-3 : Both primary and secondary
forces are balanced
6. A wheel rotates with a constant acceleration of 2.0 rad/s2. If the wheel starts from rest, the
number of revolutions it will make in the first 10 sec will be _______.
7. An aeroplane makes a complete half circle of 50 meters radius, towards left, when flying at
200 km per hr. The rotary engine and the propeller of the plane has a mass of 400 kg and a
radius of gyration of 0.3 m. The engine rotates at 2400 rpm clockwise when viewed from the
rear. Find the gyroscopic couple on the aircraft ____________ kN-m.
8. In a damped spring-mass system, if the mass is halved and the spring stiffness is doubled, the
logarithmic decrement is……..
9. What will be the frequency of torsional vibrations of the disc shown in figure. If both the
ends of the shafts are fixed and the diameter of the shaft is 40 mm. The disc has a mass of 96
kg and radius of gyration of 0.4 m. Take modulus of rigidity for the shaft material is 85 GPa.
L1 = 1 m and L2 = 0.8 m.
10. For the system shown in figure, the cantilever beam has flexural rigidity EI, the time period
of oscillation is
11. A block of mass 10 kg executes simple harmonic motion under the restoring force of a
spring. The amplitude and time period of the motion are 0.2 m and 3.14 s respectively. The
maximum force exerted by the spring on the block in N is ___________.
12. A 13.6 kg block is supported by the spring arrangement as shown. If the block is moved from
its equillibrium position 44 mm vertically downward and released, the maximum acceleration
of the block is ___________ m/s2.
13. What will be the natural frequency of the system shown below in _________ Hz.
MD
14. If the heat generated in the bearing is 300 J, load acting on the bearing is 16,000 N and
bearing has a speed of 600 rpm, the diameter of journal bearing is _________ mm. [Take
coefficient of friction as 0.01].
15. A shaft can safely transmit 180 kW while rotating at a given speed. If this shaft is replaced by
a shaft of diameter double of the previous one and rotated at half the speed of the previous,
the power that can be transmitted by the new shaft is __________ Kw
16. Two plates are joined together by means of single transverse and double parallel fillet welds
as shown in the given figure. If the size of fillet is 5 mm and allowable shear load per mm is
300 N, what is the approximate length of each parallel fillet?
17. A helical spring is made from a wire of 6 mm diameter and has outside diameter of 75 mm. If
the permissible shear stress is 350 MPa and modulus of rigidity 84 kN/mm2. By considering
the effect of curvature the deflection per active turn will be
18. A multiplate disc clutch transmits 55 kW of power at 1800 rpm. The coefficient of friction
for the friction surfaces is 0 .1. Axial intensity of pressure is not to exceed 160 kN/m2. The
ratio of internal radius to external radius of clutch is 0.7 and internal radius is 80 mm. Then
the number of plates needed to transmit the required torque is _____________.
19. Water is flowing through a 200 mm diameter pipe with coefficient of friction f = 0.04. The
shear stress at a point 40 mm from the pipe axis is 0.00981 N/cm2. The shear stress at the
pipe wall will be _____________ N/cm2.
20. A multi-disc clutch employs 3 steel and 2 bronze discs having outer diameter of 300 mm and
inner diameter of 175 mm. If the coefficient of friction is 0.25 and axial force on each pair of
surfaces is 5 kN, then the torque transmitted assuming uniform wear is _________ N-m.
21. A shaft rotating at constant speed has variable load applied to it. The radial load on a bearing
is F1 equal to 3 kN for 1 second, F2 equal to 1.5 kN for 2 seconds, and F3 equal to 500 N for
3 seconds. If the load variation subsequently repreats itself then the equivalent load Fm is
__________ kN.
FM
22. An orifice meter with Cd = 0.61 is substituted by venturimeter with Cd = 0.98 in a pipeline
carrying crude oil, having the same throat diameter as that of the orifice. For the same flow
rate, the ratio of the pressure drops for the venturimeter and the orifice meter is __________.
23. A vertical venturimeter 40 cm × 20 cm is provided in a vertical pipe to measure the flow of
oil of relative density 0.80. The difference in elevations of the throat section and entrance
section is 0.5 m, the direction of flow of oil being vertically upwards. The oil mercury
differential gauge shown deflection of mercury (SHg = 13.6) equal to 40 cm as shown in
figure. The quantity of oil flowing in the pipe (Neglect losses).
24. A particle moves along a curve whose parametric equations are x = t3 + 2t, y = – 3e–2t and z =
2 sin(5t ), where x, y and z show variations of distance covered by the particle (in cm) with
time t (in s). The magnitude of the acceleration of particle (in cm/s2) at t = 0 is ____________
.
25. The flow of water (mass density = 1000 kg/m3 and kinematic viscosity = 10–6 m2/s) in a
commercial pipe, having equivalent roughness ks as 0.12 mm yields an average shear stress at
the pipe boundary = 600 N/m2. The value of ks /δ′ (δ′ being the thickness of laminar sub
layer) for this pipe is
26. A pipe of 0.7 m diameter has a length of 6 km and connects two reservoirs A and B. The
water level in reservoirs A is at an elevation 30 m above the water level in reservoir B.
Halfway along the pipeline, there is a branch through which water can be supplied to a third
reservoir C. The friction factor of the pipe is 0.024. The quantity of water discharge into
reservoir C is 0.15 m3/s. Considering the acceleration due to gravity as 9.81 m/s2 and
neglecting minor losses the discharge (in m3/s) into the reservoirs B is __________.
HMT
27. In order to increase rate of heat transfer metal rods are used as fins. If the long metal rods
have dia 15 cm and coefficient of heat transfer as 15 W/m2K. The minimum value of ‘k’ so
that the use of fin is justified is _____________W/mK.
28. A cylindrical uranium fuel rod of radius 5 mm in a nuclear power plant is generating heat at
the rate of 4 × 107 W/m3. The rod is cooled by a liquid (convective heat transfer coefficient
1000 W/m2K) at 25°C. At steady state, the surface temperature (in K ) of the rod is….
29. In a flow over flat plate, water with velocity 6 m/s and stanton number = 0.3096 × 10–3, if
velocity is doubled with stanton number remaining constant. Then the new heat transfer
coefficient will be _________ W/m2K.
Use ρ = 1000 kg/m3 k = 4.2 W/Mk cp = 4.18 kJ/kgK
30. Solar radiation of 1200 W/m2 falls perpendicularly on a gray opaque surface of emissivity
0.5. If the surface temperature is 50°C and surface emissive power is 600 W/m2, the radiosity
of that surface will be _____________W/m2
THERMODYNAMICS
31. The piston of a vertical piston-cylinder device containing a gas has a mass of 40 kg and
cross-sectional area 0.04 m2. The atmospheric pressure is 0.95 bar. The pressure inside the
cylinder is
32. In a piston-cylinder arrangement, the pressure is inversely proportional to the square of
volume. The initial pressure is 10 bar in cylinder and initial volume is 0.1 m3. The volume is
now changed so that the final pressure is 2 bar. The work done is
33. If a certain amount of steam is produced at a pressure of 8 bar and dryness fraction 0.8. What
is the internal latent heat of steam at 8 bar ?Vg=0.240 Hfg=2046.5
34. A 100 kg block of iron casting at 500 K is thrown into a large lake that is at a temperature of
285 K. The iron block eventually reaches thermal equilibrium with the lake water. Assuming
on average specific heat of 0.45 kJ/kgK for the iron, the entropy generated during the process
is ______ kJ/K.
35. The ratio of work input needed to isentropically compress the saturated steam from 1 bar to 5
bar and work input needed to isentropically compress the saturated water for the same
pressure ratio is ______________.H1=2675 at 1 bar H2 for superheated steam at 5 bar
specific volume of water=0.001043
36. A 100 ohm resistor carrying a constant current of 1A is kept at a constant temperature of
27°C by a stream of cooling water for a time-interval of 1s, the change in entropy of resistor
is________ J/K
37. A fan is to accelerate quiescent air to a velocity of 8 m/s at a rate of 9 m3/s. The density of air
is 1.18 kg/m3. The minimum power to be supplied to fan is ________ W
38. A gas undergoes a reversible adiabatic compression process in compressor from 0.5 MPa, 0.2
m3 to 0.05 m3. It follows the law PV1.3 = constant. What is the change in enthalpy during the
process?
39. Consider the expansion of air through a very small constriction in a pipe from pressure and
temperature, respectively of 8 bar and 600 K to pressure of 1.2 bar. Assume air to be an ideal
gas. The temperature of surroundings is 25°C. Then the Irreversibility associated with the
expansion will be ____________ kJ.
RAC
40. A building requires a 2-tonne heat pump for maintaining the interior space at 27°C when the
outside temperature is 5°C. The heat pump operates on the normal vapour compression cycle
and uses R- 134a as the working fluid. The heat pump operating conditions require an
evaporator pressure of 240 kPa and a condenser pressure of 1600 kPa while the compressor
has an isentropic efficiency of 85 percent.
The COP of heat pump
is
41. A 6 m × 6 m × 4 m room contains air at 25°C and 100 kPa at a relative humidity of 75
percent. The enthalpy per unit mass of the dry air is _______ kJ/kg d.a. [Take Psat at 25°C =
3.1698 kPa].
42. In a 3 ton capacity water cooler, water enters at 30°C and leaves at 15°C steadily. The water
flow rate is __________ kg/hr.
43. An air-conditioned room of volume 20 m3 has infiltration of air equivalent to 4 air changes
per hour. Density of air is 1.2 kg/m3, specific heat cp is 1 kJ/kgK and temperature difference
between room and ambient air is 40 K. The sensible heat load due to infiltrated air is
_____________kW.
44. A stream of moist air (mass flow rate = 10.2 kg/s) with humidity ratio of 0.02 kg/kg dry air
mixes with a second stream of superheated water vapour flowing at 0.4 kg/s. Assuming
proper and uniform mixing with no condensation, the humidity ratio of the final stream (in
kg/kg dry air) is
TURBO MACHINE
45. A centrifugal pump handles liquid whose kinematic viscosity is three times that of water. The
dimensionless specific speed of the pump is 0.183 revolution and it has to discharge 2 m3/s of
liquid against a total head of 15 m then the speed (rev/s) of the turbine is ________.
46. A gas turbine plant operates on Brayton cycle using an optimum pressure ratio for maximum
net work output and a regenerator of 100% effectiveness. If the maximum and minimum
temperatures of the cycle are 800°C and 30°C respectively, the maximum network output per
kg is _________ Kj
PRODUCTION
47. While cooling, a cubical casting of side 50 mm undergoes 4%, 5% and 6% volume shrinkage
during the liquid state, phase transition and solid state respectively. The volume of metal
compensated from the riser is _________%
48. An aluminium billet of 250 mm diameter is extruded with an extrusion ratio 10. If the
effective flow stress in compression is 300 MPa. Then the ideal extrusion pressure (in MPa)
is _________
49. It is required to reduce the 15 mm diameter of steel to 12 mm with a die. The semidie angle
is 8° and the coefficient of friction is 0.06. Mean flow stress is given as 700 MPa. Then the
drawing stress would the _____MPa.
50. In a single-pass rolling process, a 100 × 10 mm, sheet is rolled to 8 mm thickness. The roll
radius is 220 mm and rotational speed is 100 rpm. The mean flow stress in tension is 180
N/mm2. Further, this reduction is the maximum possible in a single pass. The sheet thickness
at neutral plane is 9 mm. The forward slip is
51. A 4 mm thick steel plate is cut in a shearing machine and the length of cut is 400 mm. The
shear strength of the material is 200 MPa. If the cutting blade is inclined at 2 degree and
percentage penetration is 45%, then the force required will be __________ kN.
52. The part shown in figure is to be blanked from a steel strip of 3 mm thickness. Assuming
ultimateshear strength of the material to be 200 MPa. The force required for blanking
operation would be ___________ kN.
53. A steel of diameter 10 mm is reduced to 7 mm diameter with a semi-die angle of 5° and
coefficient of friction = 0.09, flow curve equation of material is σf = 1300ε0.3 MPa. Then the
drawing stress is ___________ MPa.
54. A 0.9 m thick plate is welded by manual arc welding process using welding current of 150 A,
arc voltage of 20 V and welding speed of 5 mm/s. If the process officiency is 0.8 surface
resistance is 36 micro-ohm, the heat input will be
55. Spot welding of two 2 mm thick sheets of steel (density = 7000 kg/m3) is carried out
successfully by passing a certain amount of current for 0.1 second through the electrodes.
The resultant weld nugget formed is 6 mm in diameter and 1.6 mm thick. If latent steel of
fusion of steel is 1500 kJ/kg and effective resistance is 200 μΩ. Then the current passing
through the electrodes is
56. In a arc welding process of steel with a potential of 25V and current of 200A, the travel
speed is 5 mm/sec and the cross-sectional area of joint is 20 mm2. Heat required to melt steel
may be taken as 10 J/mm3 and the heat transfer efficiency as 0.80. Then melting effciency is
_________ %.
57. The voltage arc length characteristic of a power source is V = 10 + 20 L, where V = operating
voltage in volts and L = arc length in cm. The open circuit voltage for arc lengths ranging
from 2 to 4 mm and current from 300 to 400 amps during welding operation is __________
volts.
58. A circular disc of 400 mm diameter and 100 mm height is to forged to 50 mm height. If the
materials follows the flow equation, σf = 200 (0.02 + ε)0.42 MPa, then flow stress is equal to
__________ MPa.
59. Cylindrical pins of diameter are electroplated in a shop. Thickness the plating is
micron. Neglecting gage tolerance, the sized of the Go gage in mm to inspect the
plated component is
60. Observation of a slip gauge on flatness interferometer produced fringe counts numbering 10
and 14 for two readings. The second reading is taken by rotating the setup by 180°. Assume
that both faces of the slip gauge are flat and the wavelength of the radiation is 0.5086 mm.
The parallelism error (in mm) between the two faces of the slip gauge is ___________ μm.
61. A standard machine tool and an automatic machine tool are being compared for the
production of component. Following data refers to the two machine
What is the breakeven production batch size above which the automatic machine tool will be
economical to use?
62. A bush manufacturing company has a contract to supply 5000 bushes to an automobile
factory per day. The company has capacity to manufacture 8000 bushes and holding cost of
1000 bushes is 8 paise. Set up cost is Rs. 20. The length of production cycle is approximately
63. If orders are placed once a month to meet an annual demand of 6000 units, then the average
inventory would be __________ units.
64. The following information is provided for an item:
Annual usage = 12,000 units, ordering cost=Rs60 per order
Carrying cost = 10% of unit cost, unit cost of item = Rs. 10 and lead time = 10 days.
There are 300 working days/year. In the past two years the use rate has gone as high as 70
units per day. For a reordering system based on the inventory level, the average inventory
(units) is
65. The demand for a commodity is 100 units per day. Every time an order is placed, a fixed cost
of Rs. 800 is incurred. Holding cost is Rs. 0.16 per unit per day. If the lead time is 12 days,
the reorder point is
66. For maximization Linear Programming Problem, the objective function coefficient for an
artificial variable is
67. The arrival rate of customers at a banking counter follows Poisson distribution with a mean
of 45 per hour. The service rate of the counter clerk is 60 per hour. The probability in
percentage, of 5 customers in the queue is ___________.
68. Maximize Z = 2x1 + 3x2
subject to
2x1 + x2 ≤ 6
x1 – x2 ≥ 3
x1, x2 ≥ 0
The solution to the above
LPP is
69. Complementary function (CF ) for differential equation
70. The degree of differential equation
71. Let the eigen values of matrix [A]2 × 2 are α and β then eigen values for (A + 5I)–1 are
72. The natural frequency of vibration of the following system is ______________ rad/s. [Take g
= 10 m/s2, EI = 200 Nm for the beam]
73. An exhaust fan, rotating at 1000 rpm is to be supported by four springs, each having stiffness
kN/m. If only 10% of the unbalanced force is to be transmitted to the base, the value of K is
_____ N/m. Assume mass of the fan is 40 kg.
74. The entropy of fixed amount of an ideal gas
decreases in every isothermal compression
increase in every isothermal compression
remains same in every isothermal compression
may increase or decrease in every isothermal compression
75. A tank fully insulated contains 1 m3 of air at 50°C and 2 MPa. The valve is open and air
escapes until half the original mass is gone and then the valve is closed. After valve is closed,
the pressure inside the tank is
76. 100 kJ of energy is transferred from a heat reservoir at 1000 K to a heat reservoir at 500 K.
The ambient temperature is 300 K. The loss of available energy due to heat transfer processes
is __________ kJ.
77. Air enters an air turbine at a pressure of 700 kPa, 65°C with a velocity of 90 m/s and leaves
the turbine at 140 kPa, 5°C and 60 m/s velocity. There is no heat transfer from the turbine.
Assume air to be an ideal gas with constant specific heat. The second law efficiency of the
turbine is _________%. (Assume T0 = 25°C, p0 = 101.325 kPa
78. The specific enthalpy of the working fluid is labelled on the diagram in kJ/kg. The steam
flow rate is 12600 kg/hr. The thermal efficiency of the plant is ____________%.
79. The time study data of a lathe in a factory during a calender month is given below :
Total working hours = 400
Total maintenance hours = 100
Total hours of actual work = 240
The percentage utilization of the equipment is ______________ %.
80. A company produces two types of toys : P and Q. Production time of Q is twice that of P and
the company has a maximum of 2000 time units per day. The supply of raw material is just
sufficient to produce 1500 toys (of any type) per day. Toy type Q requires an electric switch
which is available @ 600 pieces per day only. The company makes a profit of Rs 3 and Rs 5
on type P and Q respectively. For maximization of profits, the daily production quantities of
P and Q toys should respectively be
81. A curve y = is allowed to revolve around x axis. The volume of solid of revolution for 2 ≤
x ≤ 3 is
82. A complex number is defined as z = where i is the square root of negative unity.
The simplified value of z is approximately
83. The integral is evaluated by changing the order of integration, that leads
to The value/expression for q and s are respectively
84. The vectors from origin to the points A and B are respectively. The
area of the triangle OAB _________ unit2. (where O is origin)
85. In a lottery, 20 tickets are drawn at a time out of 50 tickets numbered from 1 to 50. The
expected value of the sum of the numbers on the tickets drawn is ____________.
86. The solution of the differential equation
87. A function f (x) is defined as For f (x) to be a valid probability
density function the value of A must be
88. If a triangle ABC has vertex points A(0, 0), B(1, 0) and C(0, 1), then the value of integral
evaluated over the triangle is
89. If the probability of a bad reaction from a certain injection is 0.001, then the probability that
out of 2000 individuals more than two will get a bad reaction is
90. If a force displaces a particle in the xy plane from (0, 0) to (1, 4) along a
curve y = 4x2, then the work done by the force is
91. A player tosses two fair coins at a time. He wins Rs 2 if 2 heads occur and Rs 1 if 1 head
occurs. On the other hand, he loses Rs 3 if no heads occur. If the player plays for 100 times,
then the probable amount he will get is _________ `.
92. If the residue of the function at its pole is then the value of p is ______.
93. A motor of 50 W power rotates a solid shaft AB at 500 rad/s. The weight density of the shaft
AB is 12 N/m3. The maximum normal stress induced in shaft is __________ Pa.
94. The overhanging beam ABC carries a concentrated load P at end C the displacement of the
beam at C, is ___________m.
95. A sphere of diameter 5 m is subjected to a uniform pressure P = 250 MPa on all directions as
shown and the Young’s modulus of sphere is E = 200 GPa. The bulk modulus of the material
of sphere is
96. An elastomeric bearing pad is subjected to a shear force during a static loading test. The pad
has dimensions a = 150 mm and b = 225 mm and thickness t = 55 mm. The lateral
displacement of the top plate with respect to the bottom plate is 14 mm under a load P = 16
kN. The shear modulus of elasticity G of the elastomer is approximately.
97. A rod [Young’s modulus 200 N/m2 and Poisson’s ratio 0.4] of length 4 m is suspended from
the ceiling by one of its ends. The weight density of the rod is 1.2 N/m3. The relative
increment of its volume ΔV/V is ________ × 10–3.
98. An incompressible fluid is flowing through a contraction section of length L and has a 1–D
(x–direction) steady state velocity distribution, . If u0 = 2m/s and L = 3 m, the
convective acceleration (in m/s2) of the fluid at L is ___________.
99. In an orifice meter, if the pressure drop across the orifice is overestimated by 5% then the
PERCENTAGE error in the measured flow rate is ______________.
100. A turbine develops 3 MW when running at a speed of 140 rpm and under a head of 10
m. The specific speed of the turbine in S.I. unit is ______________.
101. A large airship of volume V contain helium under standard atmosphere condition (T =
15°C, p = 101.325 kPa). The density of the helium is ___________ kg/m3
102. A pump draws oil (specific gravity 0.8) from a storage tank and discharges it to an
overhead tank. The mechanical energy delivered by the pump to the fluid is 50 J/kg. The
velocities at the suction and the discharge points of the pump are 1 m/s and 7 m/s,
respectively. Neglecting friction losses and assuming kinetic energy correction factor to be
unity, the pressure developed by the pump (in kN/m2)
103. A liquid is flowing through the following piping network. The length of pipe sections
P, Q, R and S shown in the schematic are equal. The diameters of the sections P and R are
equal and the diameter of the sections Q is twice that of S. The flow is steady and laminar.
Neglecting curvature and entrance effects, the ratio of the volumetric flow rate in the pipe
section Q to that in S is ___________.
104. A liquid flowing in a pipe a head loss of 2 m in pipe length of 10 m. The Reynolds
number of the flow is 100. If the flow rate is doubled and all other properties remains the
same, the head loss is ________m.
105. A turbine is to operate under a head of 25 m at 200 rpm. The available discharge is 9
m3/s. Assuming overall efficiency of 90%. The power generated by the turbine under the
head of 20 m is _________MW.
106. A steam power station uses the following property table to evaluate the various
parameter regarding power plant performance.
Steam rate = 200 TPH
The overall heat transfer coefficient for condenser tubes is 3200 W/m2K and inlet and outlet
temperature of cooling water is 30°C and 40°C respectively. The area of tubes of condenser
is
107. The figure shows a paddle wheel coupled with an agitator submerged in a water tank
placed in a ice bath at 0°C. The thickness of the tank walls is 2 mm and with thermal
conductivity 0.5 W/m°C. The surface area of tank in contact with water is 0.05 m2. It is found
that in steady state the block goes down with constant speed of 0.1 m/s and the temperature
of water in the tank remains constant at 1°C. The mass of block is
108. For a cylinder of radius 10 mm the temperature distribution in radial direction is given
by T = 2r 2 – 4r + 5 where r (in m) is measured from centre. The cylinder is placed in
ambient at 20°C and heat transfer coefficient of 8.49 W/m2K. If the thermal conductivity of
cylinder is 30 W/mK. The wall temperature of cylinder is
109. A wall of 0.5 m thickness is to be constructed from a material which has an average
thermal conductivity of 1.4 W/mK. The wall is to be insulated with a material having an
average thermal conductivity of 0.35 W/mK so that the heat loss per square metre will not
exceed 1450 W. Assuming that the inner and outer surface temperature are 1200°C and 15°C
respectively. The thickness of insulation required is ______________ metre.
110. One end of a thermally black metallic rod of length 10 cm is inserted in a furnace
whose temperature is 827°C. The curved surface of the rod is insulated. The room
temperature is 27°C. When the steady state is attained the temperature of the other end of rod
is 702°C. The thermal conductivity of the rod is______ W/mK.
111. Oil at 150°C flows slowly through a long thin walled pipe of 30 mm inner diameter.
The pipe is suspended in a room for which the air temperature is 20°C and convection
coefficient at the outer tube surface is 11 W/m2K. The heat lost per unit length of tube is
___________W.
112. An enclosure 1 × 2 × 4 consists of three surfaces. Flat surface at the bottom 1 × 2, A1 =
2 m2, flat surface at the top 1 × 2 m, A2 = 2 m2 and all vertical surfaces taken together A3 = 24
m2. All the surfaces are flat and A1 is parallel to A2. Shape factor F1–2 = 0.035. The ratio of F13
and F3–2 will be _________.
113. Water enters a very long tube having an inner diameter of 0.01 m with velocity and
temperature 0.01 m/s and 30°C respectively. The average difference between the tube inner
surface and bulk mean temperature of water is 10°C. The value of constant and uniform heat
flux imposed on the tube is ___________ W/m2.[Take the properties of water at mean bulk
emperature of 40°C as ρ = 990 kg/m3, ν = 0.65 × 10–6m2/s; c = 4178 J/kgK, k = 0.62 W/mK;
Pr = 4.3].
114. A body emits maximum energy at 4253 Å and the same body at some other
temperature emits maximum energy at 2342Å. The ratio of the maximum energy radiated by
the body in a short wavelength range is
115. A hot cylinder ingot of 50 mm diameter and 200 mm long is taken out from the
furnace at 800°C and dipped in water till its temperature falls to 100°C, then the Biot number
will be [Take k = 60 W/m°C, h = 200 W/m2°C]
116. A metal plate of 4 mm thickness and having k = 95.5 W/m°C is exposed to gas
temperature of 100°C at one end and cooling at 25°C by water on the other side. If the heat
transfer coefficient of gas and water are 14500 W/m2°C and 2250 W/m2°C respectively. The
temperature on gas side of plate is
117. Air at 20°C flows past a 250 mm long plates at a velocity of 45 m/s. If the surface of
the plate is maintained at 300°C. Take properties of air as: k = 0.03638 W/m-K, α = 44.10 ×
10–6 m2/s, Pr = 0.682. The heat transferred from the entire plate length to air assuming unit
width of the plate will be __________ W.
118. Consider a 3m × 3m × 3m cubical furnace. The base surface is black (1) and has a
temperature of 550 K. The radiosities for the top (2) and side (3) surfaces are calculated to be
7500 W/m2 and 3200 W/m2, respectively. The net rate of radiation heat transfer to the bottom
surface is __________ kW. (Take F12 = 0.2 and F13 = 0.8)
119. Molten aluminium was poured in a sand mold and the thickness of solid skin formed
after 10 sec and 20 sec were found to be 2 mm and 4 mm respectively, then the thickness of
the solid skin at the end of 80 sec after pouring will be
120. In an interchangeable assembly, a shaft of mm diameter and a hole of
mm diameter form a mating pair. In the worst assembly condition, clearance between them
will be.
121. A vernier scale consist of 25 divisions on 12 mm spacing and the main scale has 24
divisions on 12 mm then least count of vernier scale will be _________ mm.
122. In orthogonal machining with a cutting tool having 10° rake angle, chip thickness is
measured to be 0.4 mm, the uncut thickness being 0.15 mm, then the magnitude of the shear
strain will be _________.
123. A 600 mm long shaft has a 160 mm tapered step at the middle with 4° included angle.
The tail-stock offset required to produce this tapper on lathe would be __________ mm.
124. In a conventional milling operation, if depth of cut and diameter of cutter both gets
thrice, then percentage change in maximum uncut thickness will be __________ .
125. An engine produces 12 kW brake power while working with a brake thermal
efficiency of 28%. The calorific value of the fuel used is 40,000 kJ/kg. The fuel consumption
in kg/hour is __________.
126. In a power plant, water (ρ = 1000 kg/m3) is pumped from 90 kPa to 2.5 MPa. The
pump has an isentropic efficiency of 0.85. Assuming that the temperature of the water
remains the same, the specific work (in kJ/kg) supplied to the pump is _____________.
Consider the following statements about a two-stroke engine:
P It has higher thermal efficiency.
Q : It has higher mechanical efficiency.
R : It is much easier to start a two-stroke engine than a four stroke engine.
S : For the same power developed, it is much lighter, less bulky and occupies less floor area
than a four-stroke engine
Q,R,S.
Select the CORRECT statements?
1.Mechanical efficiency of an I.C. engine as compared to gas turbine is higher.
2. Thermal efficiency of a diesel engine plant as compared to gas turbine plant is higher.
3. Thermal efficiency of petrol engine as compared to diesel engine is lower 2,3
127. In a Morse test for a 2-cylinder, 2-stroke SI engine, the brake power was 10 kW
whereas the brake power of individual cylinder with spark cut-off were 4.75 kW and 4 kW
respectively. The mechanical efficiency of the engine is
128. The engine of a car has four cylinders of 70 mm bore and 75 mm stroke. The
compression ratio is 8. The cubic capacity of the engine and the clearance volume of each
cylinder are ______ , ______ respectively.
129. A gas turbine plant operates in an air-standard Brayton cycle between the temperature
limits of 27°C and 800°C. The ratio of Carnot efficiency to the Brayton cycle efficiency for
maximum work is
130. An automobile engine operate at a fuel-air ratio of 0.06, volumetric efficiency of 92%
and indicated thermal efficiency of 32%. The calorific value of the fuel is 50000 kJ/kg and
density of air at intake is 1.2 kg/m3, the indicated mean effective pressure (in MPa) for the
engine is __________.
131. A power station produces 500 MW of power. The plant thermal efficiency is 33%. The
rise of cooling water temperature is to be restricted to 5°C. The rate of cooling water flow
required in tons per hour is _____________ × 105. (Take specific heat of the water is 4.2
kJ/kgK.)
132. If the true stress strain curve of a ductile material is represented by the equation σ =
800ε0.3, the ultimate tensile strength (engineering) will be __________ MPa
133. A turbocharged four-stroke direct injection diesel engine has a displacement volume
of 0.0259 m3. The engine has an output of 950 kW at 2200 rpm. The mean effective pressure
(in MPa) is ________.
134. In a multiple disc clutch, if there are 6 discs on the driving shaft and 5 discs on driven
shaft, the number of pair of contact surfaces will be equal to
135. If helix angle (α) is 15° and circular pitch (Pc) is 30 mm then axial pitch of helical
gear is _____ mm
136. The maximum tension in belt is 800 N, angle of wrap is 50° in tension ratio is 2 as
shown in figure, then braking effort required in the simple band brake, when drum is rotating
in clockwise direction is
137. A band brake acts on the circumference of the drum of 300 mm diameter and half of
the circumference of the drum is covered by the band. If the band provides a braking torque
of 250 N, the tension in the tight side is (Take μ = 0.3)
138. Two plate are jointed a shown in the figure.
The maximum tensile and shear stresses are 80 N/mm2 and
60 N/mm2 respectively. The plate is 70 mm wide and 15 mm thick. What will be the value of
L if the total load carried by the joint is 80 kN?
139. A forged steel bar of 50 mm diameter, is subjected to a reversed bending stress of 250
N/mm2. The bar is made of steel 40 C8 (Sut = 600 N/mm2) and the corrected endurance limit
of the bar is 101 N/mm2, then life of the steel bar will be ______cycles.
140. A pinion has 15 teeth and module of 8 mm. The gear ratio is 10 : 1 and the pressure
angle is 22.5°. The pinion transmits 500 kW at 1800 rpm then normal load on the tooth will
be ________ kN.
141. A shaft rotating at constant speed is subjected to variable load. The bearing supporting
the shaft are subjected to stationary equivalent radial load of 3 kN for 10% of the time, 2 kN
for 20% of the time, 1 kN for 30% of the time and no load for the remaining time of cycle. If
the total life expectancy of the bearing is 37 millions revolutions at 90% reliability, the
dynamic load rating of the ball bearing is___________kN.
142. A vibrating system shown in figure with a mass 40 kg, stiffness 18 kN/m and damper
having damping coefficient 54 N-s/m, when an exciting force of magnitude 64 sin(37.7 t ) is
acting, what would be the frequency of vibrations in Hz. [Approx]
143. A cam operates a knife edge follower having a lift of 30 mm. The cam raises the
follower with SHM for 180° of rotation followed by a period of dwell for 60°. The follower
descends for next 100° rotation of cam with uniform velocity, again followed by a dwell
period.The cam rotates at 120 rpm and has a least radius of 20 mm. The maximum
acceleration of follower during lift will be __________ m/s2.
144. One of the driving axles of a locomotive with its two wheels has moment of inertia of
350 kg-m2. The wheels are of 1.85 m diameter. The distance between the planes of the wheels
is 1.5 m. When travelling at 100 km/hr the locomotive passes over a defective rail which
causes the right hand wheel to fall 12 mm and rise again in total time of 0.1 sec, the vertical
movement of wheel being S.H.M. What is the maximum gyroscopic torque when the wheel
is falling?
145. Two involute gears in a mesh have a velocity ratio of 3. The arc of approach is not to
be less than the circular pitch when the pinion is the driver. The pressure angle of the involute
teeth is 20°. The least number of teeth on each gear is
146. In a spring controlled governor the curve of controlling force is a straight line. When
balls are 35 cm apart the controlling force is 1100 N and when 20 cm apart it is 550 N. To
make the governor isochronous, the required initial tension on the spring would be
_________ N.
147. The torsional pendulum with a disc of MOI 0.05 kg-m2 immersed in a viscous fluid as
shown in diagram during vibrations of pendulum, the observed amplitudes on the same side
of neutral axis for successive cycles are could to decay 50% of initial value. The damping
factor will be ___________.
148. A metal block of mass 1 kg and heat capacity C J/K at T1 K is dropped from a height Z
m into a lake at T2 K. (T1 > T2). What is the entropy change of the universe during the
process?
149. A fully charged battery gradually discharges while lying in a room at constant
temperature. During discharging, it loses 1020 kJ to the environment. The battery is then
recharged slowly to its initial state. The charging process consumes 0.7 kWh of electricity.
What is the heat transfer during the charging process?
150. One kilogram of air is in a piston-cylinder apparatus that can only exchange heat with
a reservoir at 300 K. Initially this air is at 100 kPa and 27°C. It is then compressed to 250
kPa and 27°C. The process is
151. A 2m × 5m × 10m room is to be heated by a resistance heater. It is desired that the
resistance heater be able to raise the air temperature in the room from 10°C to 25°C within 15
minutes. Assuming no heat losses from the room and an atmospheric pressure of 100 kPa, the
required power of the resistance heater is ___________ kW.
152. A mass of air is stirred by a paddle wheel in an insulated constant volume tank. The
velocities due to stirring make a negligible contribution to the internal energy of the air. Air
flows at through a small valve in the tank at the rate of 0.9 kg/h to keep the temperature in
the tank constant. At a certain instant, the pressure and tank volume are found to be 1 MPa
and 0.15 m3 respectively. If the power to the paddle is 0.2 kW, the temperature of air in the
tank is ____________ °C.
153. The specific exergy of air for a state at 2 bar, 600 K when surrounding are at 1 bar,
300 K is ______kJ/kg.
(Take cp = 1 kJ/kgK and R = 0.3 kJ/kgK)
154. A power plant operates at 30% efficiency during summer when the sea water used for
cooling is at 25°C. The plant uses 350°C steam to drive turbines. If the plant’s efficiency
changes in the same proportion to ideal efficiency, the plant efficiency in winters when the
sea water is 10°C is:
155. A reversible heat engine operates with three thermal reservoirs and delivers 50 kW
power. The engine absorbs 1000 kJ/s from a reservoir at 600 K. The temperature of the other
reservoirs are 400 K and 300 K. The thermal efficiency (in %) of the engine is ___________.
156. Air at 3 bar and 400°C is contained in a cylinder fitted with a piston and a set of stops
as shown in the figure. The air is cooled as a result of heat transfer to the surroundings
making the piston reach the stops. The pressure of air when its temperature becomes equal to
room temperature of 20°C is ______bar.
157. A household refrigerator is maintained at a temperature of 2°C. Each time the door
opens, warm food is placed inside introducing an average heat of 400 kJ. The refrigerator
operates at 20% of the ideal COP. The monthly bill at the rate of Rs. 3 per kWhr is Rs. 200. If
the atmosphere is at 27°C, the number of times in a day the door is opened is ________
158. One kg of steam expands following the law pvn = constant. Initial pressure of steam
and dryness fraction are 10.5 bar and 0.9 respectively. The final pressure and volume are 1.05
bar and 0.679 m3. If the density of saturated liquid and saturated vapor at 10.5 bar are 990
kg/m3 and 5.15 kg/m3 respectively, the index n of expansion is __________.
159. The sales units, selling price per unit and variable cost per unit for A, B and C are
indicated in the table below.
Taking fixed cost of Rs. 40,000 the break even sales is ___________.
160. A contractor has to supply 5000 bearings per day to an automobile manufacturer. He
finds that, when he starts a production run, he can produce 15000 bearings per day. The cost
of holding a bearing in stock per one year is Rs. 2 and the setup cost of a production run is
Rs. 1,100. How frequently should the production run be made? (Take number of working
days in a year = 300)
161. An auto company manufactures cars and trucks. Each vehicle must be processed in the
paint shop and body assembly shop. If the paint shop were only painting trucks, then 40 per
day could be painted. If the paint shop were only painting cars, then 60 per day could be
painted. If the body shop were only producing cars, then it could process 50 per day. If the
body shop were only producing trucks, then it could process 50 per day. Each truck
contributes $300 to profit, and each car contributes $200 to profit. What will be the
maximum profits of the company?
162. Patients arrive at a clinic at the rate of 4 per hour and are examined at the rate of 5 per
hour. If there is a restriction of 10 people, the probability (in percentage) that a patient is
forced to leave without joining the queue is __________.
163. If A is a 3 rowed square matrix such that its determinant is|A|, then |adj(adj A2)| is
equal to
164. The orthogonal trajectories of the family of curves y = cxk are given by
165. The maximum distance of the point (3, 4, 12) from the point which lies on the sphere
x2 + y2 + z2 = 4 is _________ units.
166. If z = up till n times.
167. The value of the integral is evaluated over the curve c which
is defined by | z | = 4. The value of k is ___________.
168. Which of the following apparatus will independently measure the dynamic pressure of
the fluid flowing in the pipe?
169. A 15 kg block slides down an incline of 30° on a 0.1 mm film of SAE oil μ = 8.14 ×
10–2 Pas. Area of contact is 0.25 m2. The terminal velocity is
170. A smooth pipe 30 cm in diameter and 100 m long has a flush entrance and submerged
discharge. The velocity is 3 m/s. If the fluid is water at 15°C the total loss of head is
_________ m. Take f = 0.0122.
171. In a Pelton wheel, the bucket angle is 165° and the ratio of peripheral velocity to jet
velocity is 0.46. The hydraulic efficiency is __________%.
172. In a Pelton wheel installation the effective head is 180 m and Euler head is 168 m. The
turbine develops 3750 kW shaft power and 4475 kW power is developed by the runner. The
overall efficiency is ______%.
173. In a Pelton wheel, the diameter of the wheel is 2 m and the angle of deflection is 162°.
The jet diameter is 165 mm and the pressure behind the nozzle is 1000 kPa. The hydraulic
efficiency when the wheel rotates at 320 rpm is
174. An inward flow turbine with radial discharge works under a head of 8 m and the
peripheral velocity at inlet is and flow velocity is If the hydraulic
efficiency is 85%, the velocity of whirl at inlet is __________ m/s.
175. Saturated steam at atmospheric pressure is available on a plate maintained at T1°C by
circulating cooling water through the other side. The rate of dripping of the condensate of the
plate is x when the plate is vertical. When the plate is tilted at an angle of 45°, the rate of
condensate dropping becomes.
176. Two horizontal steam mains with diameters d1 and d2 are laid in a boiler house such
that any mutual heat effect is precluded. The mains are at the same surface temperature. What
is the ratio of heat transfer coefficient h1/h2 for one meter length of the mains?
177. When modelling unsteady conduction in a semi-infinite slab with convection at the
surface, the appropriate length scale is:
178. Heat flows along the axis of a solid which has the shape of a truncated cone with
circumferential surface insulated as shown in the figure. The base plane (at x = 0) is at 400°C
and the area of section at distance x from base of the cone is given by:
179. A = 1 – 2.5x (where x is in meters)
180. If the plane at x =0.2 m is maintained at 50°C, the temperature gradient at x = 0 is
__________ °C/m.
(Take thermal conductivity of solid material = 2 W/mK)
181. Two identical heated plates are exposed to still air, thus generating natural convection.
One plate is vertical with a Grashoff number of Gr1, while the other faces down at an angle of
45 degrees and has a Grashof number of Gr2. The ratio Gr2/Gr1 is ___________.
182. A long, circular aluminium rod attached at one end to a heated wall transfer heat
through convection to a cold surrounding fluid. If the diameter of the rod is tripled, the
percentage change in the rate of heat removal is ________.
183. Consider turbulent flow of a fluid through an isothermal square channel. The
percentage change in the rate of heat transfer when the free-stream velocity is tripled is
____________.
184. A 5 cm diameter, 1 m long shown in the figure is having its lower circular face
grinded smooth. The remainder of the rod is exposed to 30°C room air and a surface
coefficient heat transfer equal to 7 w/m2K exists between the rod surface and the room air.
The grinder dissipates mechanical energy at the rate of 20 W. If the thermal conductivity of
rod material is 40 W/mK, what is the temperature of the rod at the point where the grinding is
taking place?
185. A solid aluminium sphere of diameter D and emissivity ε, initially at a high
temperature is cooled by convection and radiation in a chamber having walls at lower
temperature. Convective cooling is achieved with a gas passing through the chamber at T∞
temperature resulting in a convective heat transfer coefficient of h. Taking the emissivity of
aluminium as ε and the density and specific heat as ρ and c respectively, the variation of
sphere temperature with time during cooling process can be predicted by which of the
following differential equations?
186. A horizontal semi-transparent plate is uniformly irradiated from above and below
while air at T = 300 K flows over the top and bottom surfaces, providing a uniform
convection heat transfer coefficient of h = 40 W/m2K. The total hemispherical absorptivity of
the plate to the irradiation is 0.4. Under steady state conditions, measurements made with
radiation detector above the top surface indicate a radiosity (which includes transmission,
reflection and emission) of 5000 W/m2, while the plate is at a uniform temperature of 350 K.
What is the emissivity of the plate?
187. The temperature variation within a slab of thickness 50 cm is given by the relation:
t x = 100 + 200x – 200x2
Where t is in °C and x is the distance measured from one face in meters. Taking unit area
normal to the direction of heat transfer, the heat generation rate per unit volume inside the
slab is __________ W. (Take thermal conductivity of slab material as 50 W/mK)
188. Two long copper rods of diameter D = 1 cm are soldered together end to end with
solder having melting point of 650°C. The rods are exposed to air at 25°C with a convection
heat transfer coefficient of 10 W/m2K. The minimum electrical power input needed for the
soldering to occur is _______ W. (Thermal conductivity of copper = 379 W/mK).
189. A diffusely emitting surface is exposed to a radiant source causing the irradiation on
the surface to be 1000 W/m2. The intensity of emission is 143 W/m2·sr and the reflectivity of
the surface is 0.8. The net heat flux to the surface by radiation is ______________ W/m2.
190. A 10 mm diameter mild steel sphere (k = 45 W/mK) initially at temperature of 500°C
is exposed to air flow at temperature 25°C resulting in convective heat transfer coefficient h
= 100 W/m2K. The properties of mild steel are Density=7850 kg/m3, Specific heat = 450
J/kgK, Thermal diffusivity=1.2×10–5m2/s The total energy transferred from the sphere during
the first one minute is __________ W.
191. A cold storage consists of a cubical chamber of dimension 2m × 2m × 2m, maintained
at 10°C inside temperature. The outside wall temperature is 35°C. The top and side walls are
covered by a low conducting insulation with thermal conductivity k = 0.06 W/mK. There is
no loss of heat from the bottom. If the heat loss through the top and side walls is to be
restricted to 500 W, the minimum thickness of insulation required is _____________ mm.
Which one of the following statement is not correct? End milling cutter are combination of
both slab milling and face milling operation. When milling is performed on two surfaces
simultaneously, it is known as straddle milling. Producing screw thread over a lathe is known as
thread chasing. Tapping is a process of creating internal threads.
192. In sand casting of hollow part of zinc, a cylindrical core of diameter 130 mm and
height 200 mm is placed inside the mould cavity. The densities of core material and zinc are
1500 kg/m3 and 12000 kg/m3 respectively. The net force that tends to lift the core during
pouring of molten metal will be_____ N.
193. A 20 mm wide and 4 mm thick C20 steel sheet is required to be bent at 60° at bend
radius 10 mm. Then the bend allowance will be _____________mm.
194. A spectrometer gives the following reading when used to measure the angle of prism.
Main scale reading = 58.5 degree. Vernier scale reading = 9 division Given that 1 division on
main scale corresponds to 0.5 degree. Total division on the vernier scale is 30 and match with
29 divisions of the main scale. The angle of prism from the above data is:
195. Consider the following data pertaining to a typical surface grinding operation: Wheel
diameter = 160mm Cutting depth = 0.04 mm Workpiece velocity = 400 mm/s Grain velocity
= 25 m/s What is the undeformed chip length?
196. What is the percentage of CO during the combustion of ethene (C2H4) in the oxygen
atmosphere when 2.5 moles of oxygen is available?
197. A four stroke single cylinder engine with brake mean effective presssure of 5.5 bar
produces 100 kW power. What is the swept volume (in litres) if the engine speed is 2400
rpm?
198. For BCC iron, the interplaner spacing is 0.1013 nm. What is the diffraction angle for
the (220) set of planes if the lattice parameter for iron is 0.2866 nm, monochromatic radiation
having a wavelength of 0.1790 nm is used and order of reflection is 1?
199. In an open cycle gas turbine, with regeneration air enters the compressor at a pressure
of 1 bar and leaves at a temperature of 350 K. The maximum temperature in the cycle is
1050K. Air flowing at the rate of 10 kg/s through the cycle expands isentropically in the
turbine attaining an exhaust temperature of 750 K. If the heat supplied during combustion
process is 5500 kW, the effectiveness of the regenerator is ____________ percent.
200. The stroke and bore of a two stroke S.I. engine are 150 mm and 100 mm respectively.
The compression ratio is 8.5. If the specific heat ratio is 1.4, the clearance volume is
__________ cm3.
201. A steam turbine plant is equipped with a single regenerative feedwater. Steam at an
initial pressure of 16 bar with an enthalpy of 3000 kJ/kg enters the turbine. It is extracted at 2
bar where its enthalpy is 2600 kJ/kg. Exhaust steam comes out at a pressure of 0.05 bar and
enthalpy 2115 kJ/kg. If the thermal efficiency of the cycle is 34%, the condenser duty with
regeneration is
(The enthalpy of saturated liquid at 2 bar and at 0.05 bar is 505 kJ/kg and 140 kJ/kg
respectively)
202. In an ideal Brayton cycle, atmospheric air at 300 K enters the compressor at the rate of
3.78 × 105 kg/h attaining a maximum temperature of 1500 K. If heat is supplied to the air at
the rate of 120 MW, the back work ratio is
203. In an engine working on dual combustion cycle, the pressure at the beginning of the
compression is 1 bar. The heat supplied per kg of air is 1500 kJ, half of which is supplied at
constant volume and half at constant pressure. The maximum pressure in the cycle is 72 bar.
If the compression ratio is 13 : 1, what is the temperature of the air at the beginning of
compression? (Take cV = 0.7 kJ/kgK and γ = 1.4)
204. In an air standard Otto cycle, the ratio of maximum and minimum temperatures is 6.
The compression ratio is 5.2. What is the maximum to minimum pressure ratio in the cycle?
205. A six cylinder, four stroke spark ignition engine of 10 cm bore and 15 cm stroke gives
a brake specific fuel consumption of 0.5 kg/kWh with a mean effective pressure of 5.4 bar.
The engine speed is 4800 rpm. What is the rate of fuel consumption in kg/min?
206. An open cycle gas turbine plant operates with a pressure ratio of 4.5 while using 81
kg/min of air and1.5 kg/min of fuel. The plant gives a net output of 250 kW when 220 kW is
needed to drive the compressor. Air enters the compressor at 1 bar and 15°C and combustion
gases enters the turbine at 760°C. The specific heats of air and combustion gases are 1.005
kJ/kgK and 1.13 kJ/kgK respectively, the index of compression is 1.4 and the index of
expansion is 1.3. The mechanical efficiency for both compressor and turbine is 0.98 each.
The isentropic efficiency of the compressor is ____________ percent.
207. Two steam turbines A and B operate with same initial pressure 15 bar and same degree
of superheat 80°C. The exhaust pressure in turbine A is 0.1 bar and that in turbine B is 0.03
bar. The exhaust steam rejects 2200 kJ/kg of heat at 0.1 bar and 2000 kJ/kg of heat at 0.03
bar. The enthalpy of steam entering the turbine in both cases is 3039 kJ/kg. Following table is
provided.
The reduction in steam consumption due to lower exhaust pressure in turbine B is _________
kg/kWh.
208. A two cylinder, 4 stroke, SI engine develops a maximum barke torque of 120 Nm at
2500 rpm. The brake mean effective pressure at the maximum engine torque point is 700
kPa. If bore is equal to stroke, then the stroke volume will be ________ cc.
209. A spray cooling coil is used to operate under the following conditions: Air inlet =
30°C DBT, 21°C WBT Air outlet = 12°C DBT, 6°C WBT Total air flow rate = 2100 m3/min
If the chilling water inlet and outlet temperature are 5°C and 15°C. What is the water flow
rate through the coil? Properties of moist air from psychrometric chart are as follows :
The following statements are TRUE Low molecular weight refrigerants have high latent heat
of vaporization. For saturated state at the inlet to the compressor, a refrigerant having high
vapour specific heat may give rise to wet compression.
210. The air in a room is to be conditioned to a temperature of 21°C using a cooling coil
having ADP temperature of 12°C. The humidity of saturated air at 12°C is 0.25 kg w.v./kg
dry air. The outside air conditions are 30°C DBT, 23° WBT and 0.7 kg w.v./kg d.a. absolute
humidity. The moisture content of air being supplied to the room is ____________ kg w.v./kg
dry air.
211. An electrical heater heats 0.1 m3/s of air from 15°C and 80% RH to 55°C. The
barometric pressure at 15°C is 100 kPa and the saturation pressure is 1.625 kPa. The mass
flow rate of dry air through the heater is _____________ kg/s.
212. 0.2 kg/s of moist air at 45°C (DBT) and 10% RH is mixed with 0.3 kg/s of moist air
and temperature T°C and a humidity ratio of 0.018 kg w.v./kg d.a. in an adiabatic mixing
chamber. After mixing, the mixed air is heated to raise its temperature by 7°C. If the final
temperature at the exit of heater is 40°C. The value of T (in °C) is ___________.
213. A cooling tower is used for cooling the condenser water of a refrigeration system. In
the tower, air enters at 35°C (DBT) and 24°C (WBT) and leaves at a DBT of 26°C and
relative humidity of 95%. The flow rate of air at the inlet to the cooling tower is 19 kg/s. The
amount of make-up water required is ___________ g/s.
Following data is provided from psychrometric chart.
214. An air conditioned space is maintained at 27°C DBT and 50 percent relative humidity.
The ambient conditions are 40°C DBT and 27°C WBT. The space has a sensible heat gain of
14 kW. Air is supplied to the space at 7°C saturated. The following table is provided :
The mass of moist air supplied to the space is ___________ kg/h.
215. A water cooler using R12 refrigerant flowing at the rate of 0.5 kg/s works between
30°C and 9°C. Assuming the volumetric and mechanical efficiency of the compressor to be
90% and 80% respectively, and the mechanical efficiency of motor to be 90%, the power
requirement of the motor is _________kW.
Given cp(saturated vapour at 30°C) = 0.7 kJ/kgK. The properties of R12 at 30°C and
9°C are:
216. The specific volume of dry air in an air-water vapour mixture having temperature
24°C relative humidity 40% at standard barometric pressure 100 kPa if the saturated air
pressure is 20 kPa is
Which of the following statements is not correct in the context of structures?
In a frame, it is not necessary that all forces are along the members
There is never a need to dismember the structure for finding out the support reactions.
A member of the truss is either in tension or compression
An ideal truss, does not transmit moment among the connecting members
217. The number of degrees of freedom of the following mechanism are:
(Note that link 5 is parallel and equal in length to link 2 and link 4, also link 1 and link 3 are
equal and parallel)
218. A simply supported beam of length 5 m carrier a uniformly increasing load of 800
N/m from one end to 1600 N/m at the other end. The larger of the two reactions is
219. A single stage reciprocating compressor takes in air at 2 bar, 305K. The polytropic
compression and expansion follow the relation pv1.3 = constant and pv1.25 = constant
respectively. If the clearance volume is 5% of the swept volume, the maximum theoretical
pressure to which the air can be compressed is nearly
220. Evaluate the integral , along the straight line from z = 0 to z = 1 + i
221. The value of integral
222. The standard time of an operation is 20 min. The worker was rated at 120% and the
allowances are 25%, the obeserved time (in minutes) would be _________.
223. In an inventory model, the economic lot size is twenty five percent of the quantity
ordered at a time. The value of model sensitivity is __________.
224. In a hot working operation the strength constant C = 30000 N/m2 and strain rate
sensitivity exponent m = 0.15. The flow stress is ________ kPa at the strain rate of 0.01 s–1.
225. A drilling operation is performed with a 25.4 mm dia twist drill in a steel workpiece.
The blind hole depth is 50 mm and point angle is 118°. The cutting speed is 25 m/min and
feed = 0.25 mm/rev. The cutting time required to complete the operation is __________
seconds.
226. A disk of dia 40 cm and 5 cm thick is to be casted out of pure aluminium is an open
mold operation. Melting temperature of Al = 660°C, pouring temp. = 800°C. Assume that the
amount of aluminium heated will be 5% more than that needed to fill the mould cavity.
Compute the amount of heat (MJ) added to aluminium starting from room temperature of
25°C. Specific heat of Al(both cold and heated) = 0.88 J/g°C. Heat of fusion = 389.3 J/g.
Density Al = 2.70 g/cm3. Give answer in mega joules.
227. A fluid contained in a horizontal piston-cylinder arrangement is agitated by a paddle
wheel rotating at a uniform speed of 50 rad/s for 1000 seconds. During the process, the
piston of area 0.3m2 slowly moves at a distance of 0.5 m against a pressure of 100 kPa. If net
work done by the fluid during the process is 5 kJ, the torque in the motor shaft of the paddle
wheels:
1. PM allows formulation of alloys having constituents which have similar properties only.
2. PM metal powders are expensive.
3. Variation in density in a PM component can be troublesome.
4. Only conductive metals can be processed. 2 and 3
228. Combination of single transverse and double parallel fillet weld joints is shown below:
If the plate thickness is t and allowable shear stress() is half of allowable limits stress(σ), then
the maximum load P that the joint can withstand is:
229. A cage weighing 60 kN is attached to the end of a steel wire rope. It is lowered down a
mine shaft at am constant velocity of 1 m/s. What is the maximum stress (in MPa) produced
in the rope when the supporting drum is suddenly jammed? Free length of the rope at
moment of jamming = 15 m, area of cross-section = 25 cm2, E = 2 × 105 N/mm2. Self weight
of rope is neglected.
230. Four masses m1, m2, m3 and m4 200 kg, 300 kg, 240 kg, and 260 kg are rotating in
corresponding radius of rotation 0.2 m, 0.15 m, 0.25 m and 0.3 m respectively. The angles
between successive masses are 45°, 75° and 135°. What is the magnitude of required
balancing mass rotating at the radius of 0.2 m ?
231. A fluid undergoes a reversible adiabatic compression in a device from an initial state
of 100 kPa, 0.5 m3 to a final of 500 kPa 0.15 m3, following the law pV1.3 = constant The
change in enthalpy for the process is
232. If X is a variable has a Poisson distribution with a mean λ, λ ≠ 0. Such that P (2) = 9P
(4) + 90P (6). Then the value of mean X is
233. Air at 20°C forms a boundary layer near solid wall, in which the velocity profile is
sinusoidal given by v = vmax . The boundary layer thickness is 7 mm and peak
velocity is 9 m/s. The shear stress (Pa) in the boundary layer thickness at y = 3.5 mm is
_______. (Take μ = 1.81 × 10–5 Ns/m2)
234. A spherical metal (k = 15 W/mK) ball of radius 0.5 m is heated in an oven and then
taken out and allowed to cool in ambient of air of temperature 25°C with an average heat
transfer coefficient of 20 W/m2. If the temperature profile varies as T(r, t) = 50r 2t + 10r + t +
C1, the value of C1,1 second after being taken out of the oven is _________..
[Assume heat transfer to surroundings through convection only] [where t = time, r = radius]
235. A centrifugal compressor running at 10,000 rpm consumes 200 kJ/kg power. The
blades are inclined and the slip factor is 0.9. The inlet velocity triangle for the compressor is
given below:
The blade speed at outlet is __________ m/s.
236. In a gas turbine power plant, air from atmosphere at 300K temperature is compressed
followed by expansion in two turbines of equal pressure ratio with reheat to a maximum
cycle temperature of 1200K. The isentropic efficiency of both compressor and turbines are
90%. The pressure ratio across each turbine which gives the optimum specific output is
____________.
237. A series of cold rolling operations are to be used to reduce the thickness of a plate
from 50 mm to 25 mm in a reversing two high roll mill. Roll dia = 700 mm, coefficient of
friction between rolls and work = 0.15. Minimum number of passes required are
____________.
238. An auditorium has to be air conditioned through a process 1-3 as shown in the figure
below. Dehumidification of air takes place through a coil with bypass factor of 0.25 at the
rate of 0.0833 kg/s. If the specific volume at inlet of coil is 0.9 m3/kg, the free air to the
circulated is _________ cmm.
239. The rate of arrival of customers at a restaurant follows Poisson distribution with an
average time of 5 mintues between 2 customers. The mean service time is 2 minutes. The
probability (in percent) that 4 customers arrive in a duration of 20 minutes is ___________.
240. The simplex table given below shows the initial basic feasible solution for the
objective function
Max Z = 2x1 + 4x2, after the introduction of slack variables S1 and S2.
After the first iteration, the solution of the simplex problem is improved by _______ units.
241. During motoring test of an engine, the generator develops on electric power of 80 kW
with an efficiency of 80%. The engine is then stopped and engine shaft connected to a motor
is run at the same speed. The motor consumes 15 kW with a motor rating of 90%. The
mechanical efficiency of the engine is ____________ percent.
242. Consider a diagonal matrix If the determinant = 25, then the minimum
value of the sum of eigen values (λ1, λ2) i.e. (λ1 + λ2) is _________.
243. Given If ‘s’ represents the portion of sphere ,
then is __________.
244. A particular system maintained at constant volume has a heat capacity varying with
temperature (in K) as Cv = A + 0.01T
As the source is cooled from 127°C to the surrounding temperature of 7°C, its entropy
reduces by 0.9 kJ/K. What is the value of A?
245. In an air conditioner, a cooling coil with surface temperature equal to ADP
temperature is used for refrigeration. The enthalpy difference (in kJ/kg) between the states
are indicated in the chart below. The bypass factor for the coil is
What could be the possible modes of failures of the following riveted joint?
I : Tearing of the plate across the row of rivets.
II: Shearing of the rivets.
III: Shearing of the plates.
IV: Crushing of plates or the rivets. I, II and IV
246. An impulse turbine has equiangular blades with a nozzle exit flow angle of 25°. The
maximum value of rotor efficiency considering 15% friction losses along the blades is
247. A Pelton wheel develops 3750 kW under a head by 180 m running at 375 rpm. The
velocity ratio is ____________ for the mean bucket wheel diameter of 1.45 m.
248. There is 6 hours duty and a job should take 20 minutes to complete it. But after 6
hours, an operator is able to complete only 15 such jobs. The operator’s performance (in
percentage) is ___________.
249. A workpart having a starting height of h = 100 mm is compressed to a final height of
50 mm. During the deformation, the relative speed of the piston compressing the parts is 200
mm/s. The strain rate at height of 75 mm is ___________ s–1.
250. A spherical balloon has a diameter of 0.3 m and contains air at a pressure of 150 kPa.
The pressure is proportional to the diameter. A work of 300 kJ is done by the gas resulting in
an increase in diameter of the balloon. The increase in diameter is
251. A plane gate of uniform thickness holds back a depth of water as shown. The
minimum weight needed to keep the gate closed is approximately
252. A steel rod is subjected to a reversed axial load of 180 kN. Stress concentration factor
= 1.0. What is the required diameter the rod (in mm) for the factor of safety = 2?
253. A hollow shaft of outer radius 140 mm and inner radius 125 mm is subjected to an
axial force of 68 kN and a torque of 35 kNm. What is the maximum shearing stress in the
bar?
254. A simply supported beam is loaded with uniformly increasing load that has value zero
at one end and 8000 N/m at other end. The distance of the point of maximum bending
moment would be _____________ from the left end support.
255. A simply supported beam is loaded with a concentrated force 80 kN and a couple of
30 kNm. Determine the maximum bending moment in the beam.
256. The cross-section of the beam is as shown in figure below and the allowable working
stress in tension as well as compression is 600 MPa, determine the value of ‘b’ in cm.
257. Water flows through a 1 m long stainless steel tube in a boiler with a heat transfer
coefficient of 700 W/m2K. The inner and outer diameter of the tube are 1 cm and 1.4 cm
respectively. The convective heat transfer coefficient at the outer surface of the tube is 7200
W/m2K. Considering fouling only on the inner surface of the tube, the overall heat transfer
coefficient based on the inner surface area per unit length is 317 W/m2K. The fouling factor
is __________ m2K/kW.
258. Steam turbine is provided with a single stage of regenerative feedwater heating as
shown in the schematic diagram below. Using a stage efficiency of 80% for the turbine, the
heat rejected in the condenser is ___________ kJ/kg.
259. A refrigeration machine is required to produce ice at 0°C from water at 20°C. The
machine has a condenser temperature of 298 K while the evaporator temperature is 268 K.
The relative efficiency of the machine is 50% and 6 kg of R–12 refrigerant is circulated
through the system per minute. The refrigerant enters the compressor with a dryness fraction
of 0.6. Specific heat of water is 4.187 kJ/kgK and the latent heat of ice is 335 kJ/kg. The
dryness fraction with which refrigerant will leave the compressor is __________. The table
of properties of R–12 is given below:
260.
261. The yearly demand of a product for three consecutive years is found to be 250, 260
and 300. Further forecast is made using regression analysis. The slope of the trend line on
demand-year graph which minimizes the forecasting error is __________
262. A steel ring of internal and external diameters 65 cm and 60 cm and length 5 cm is to
be casted out of aluminium. If the shrinking allowance are as given below, the volume of
molten metal that must be poured into the mold is ________ cc.
Liquid shrinkage allowance = 0.5%
Solidification shrinkage = 3%
Solid contraction during cooling = 7.2%
263. The change in the expansion ratio of a diesel engine with compression ratio 15, if the
fuel cut-off is delayed from 4% to 8% is __________.
264. The value of where ‘C’ is the closed curve of the region
bounded by y = x2 and y 2 = x, is __________
265. A structural frame is shown in the figure, hinged at A and roller supported at D. The
total reaction at support D is
Which of the following graphs correctly represents the variation of applied pressure in case
of forward extrusion process?
266. A psychrometric process takes place along constant WBT line as shown in the figure
267. A particle of mass m is moving in a circular path of constant radius r, such that its
centripetal acceleration ac is varying with time t as ac = k 2rt 2 (k = constant). What is the
power delivered to the particle by the forces acting on it?
268. What is the design stress for a piston rod subjected to reversal of loads as per
following data? The surface of the rod is ground and surface finish factor is 0.9. There is no
stress concentration. The factor of safety = 2. The endurance limit is σe.
269. A bolt is acted upon by an axial pull of 16 kN and a transverse shear force of 10 kN.
What is the diameter (mm) of the bolt by maximum shear stress theory if the allowable shear
stress is 50 MPa?
270. Air enters at 1 bar and is compressed to 16 bar at the end of a two stage compressor
with temperatures at the inlet of first and second compressor being 27°C and 227°C. The
pressure at the exit of first compressor for minimum work is
271. A thin shield of emissivity 0.2(on both sides) is placed between two infinite parallel
plates at temperature 127°C and 527°C and reflectivity 0.8 each. The temperature of the
shield is __________ K.
272. The network for a project along with activity duration and costs are indicated in the
figure below. If the indirect cost is 10 per day, the total cost of completing the project is
_________.
273. An assembly line consists of workstations X – Y – Z with processing time per unit 30
min, 15 min and 20 min respectively. The number of workstations X required to completely
balance the assembly line is ___________.
274. A rigid tank contains air at 2 bar and 57°C. The pressure is raised by heat transfer
from a constant temperature reservoir at 407°C. The surrounding temperature is 27°C. The
loss of available energy of air due to heat transfer is
In electro discharge machining (EDM), if the thermal conductivity of the tool is high and
specific heat of the work piece is low, then the tool wear and material removal rate is expected to
be:
Low and High
A pump is installed in a pipeline, the HGL (Hydraulic grade Line) and EGL (Energy
Grade Line) for the fluid flowing left to right, when the pump is in full operation, are correctly
represented by
275. The condition to prevent self locking of the following brake is
276. The crushing stress induced between the plates and the rivet, if the load P on the joint
is 48 kN (in MPa)
P = 48 kN, t = 16 mm, d = 25 mm
277. A plate 100 mm wide and 10 mm thick is to be welded to another plate by means of a
double parallel fillets. The plates are subjected to a static load of 80 kN.What is the length (in
mm) of the weld if the permissible shear stress in the weld does not exceed 55 MPa? Allow
12.5 mm for start/stop.
278. A rigid vessel of volume 0.5 m3 contains an ideal gas at 1 kPa pressure. An extraction
pump is used to reduce the pressure inside the vessel. The gas leaves the vessel at a constant
volume flow rate of 0.02 m3/min. The time taken to reduce the pressure in the vessel to 0.5
kPa, assuming the temperature of the gas to remain constant is
279. The value of where c is the unit circle |z| = 1, is
280. The value of the integral over the region in the first quadrant for
which x + y ≤ 1, is
281. Air at a temperature T∞ flows over a flat plate with a free stream velocity of U∞. The
plate is maintained at a constant temperature of Ts. The temperature T of air at any location is
given by
where y is the distance measured from plate along its normal and δt is the thermal boundary
layer thickness. The hydrodynamic boundary layer thickness δ at the location is
___________ mm.
282. A fire engine pump delivers water to a nozzle at C situated at the end of a 100 mm dia
pipe. The velocity at the nozzle is 8.31 m/s and jet diameter is 75 mm. Neglecting major and
minor losses the power required to drive the pump is _________ kW.
283. In a double pipe heat exchanger the heat capacity rate of hot fluid is half that of cold
fluid and the inlet temperatures of hot and cold fluids are 100°C and 20°C respectively. The
ratio of the area of parallel flow heat exchanger to that of counter flow heat exchanger which
will give the same hot fluid outlet temperature of 60°C is __________.
284. The velocity diagram for an impulse wheel of diameter 1 m rotating at 4200 rpm is
shown below. Assuming an energy loss of 36 percent on the blades, the axial velocity vf2
indicated in the diagram is _____________ m/s.
285. The h-s diagram for a Rankine cycle is given below
Assuming pump work of 15 kJ/kg, the friction losses in the pump are ________ percent.
286. In a DC arc welding operation, the voltage follow: Varc = 20 + 5l where l is length of
arc, which was varied from 5 mm to 7 mm. The arc current was varied from 400A to 500A.
The open circuit voltage for the welding operation is ____________ V.
287. Moist air with enthalpy 15 kJ/kg and specific volume 0.9 m3/ kg enters a chamber at
the rate of 90 cmm. The atmospheric pressure is 1 bar. While passing through the chamber air
absorbs specific heat at the rate of 40 kW and picks up 36 kg/h of saturated steam of
saturated steam of enthalpy 2400 kJ/kg. The enthalpy of the leaving air is ____________
kJ/kg.
288. The starting solution of a transportation problem is given as follows
The increase in transportation cost if one unit is supplied from S1 to D2 is ___________ units.
289. In a production house, the maximum level of an inventory item is 100 units and is
achieved with gradual replenishment at an effective rate of 200 units per month. The
optimum quantity to be ordered each time is 150 units. The number of orders per year to
minimize the annual cost would be ________.
290. The value of K is ___________, where K
291. ir flows steadily through an air compressor at the rate of 1 kg/s. The inlet and exit
conditions are shown in the figure below:
If the ratio of inlet pipe diameter to outlet pipe diameter is 2, then the ratio of velocity at inlet
to the velocity at outlet is
292. Two refrigeration cycles are coupled, as shown in the T-s diagram below.
The enthalpies at state points are:
Neglecting any loses, the ratio of mass flow rate of refrigerant through cycle 1 to that through
cycle 2 is
293. A centrifugal air compressor delivers 20 kg/s of air consuming 5090 kW of power.
The speed of the compressor is 10000 rpm. Slip factor is 0.9 and the power input factor is
1.05. The diameter of the impeller is __________ cm.
294. The temperature profile at a particular location in a thermal boundary layer on a plate
at a temperature of 60°C exposed to ambient at 20°C is prescribed by the relation t (y) = 50 –
10y +y2The thermal conductivity of plate material is 20 W/mK. The heat transfer coefficient
is ________ W/m2K.
295. A flower vendor buys roses for 1 each and sells them for 3 each. Daily demand has the
following distribution
If each day’s demand is independent of the previous day’s, the number of papers to be
ordered each day is ________.
296. The production of ‘A’ depends on B, C, D and E as shown in the structure below:
The inventory in hand for A, C and E are 50 units, 10 units, 20 units respectively. The
scheduled receipt for D and E are 10 units, and 40 units respectively. For producing 100 units
of A, the order size of E should be of _________ units.
297. The temperature of a steel ring is raised by 150°C in order to fit on a wooden wheel of
1.2 m diameter, then the original diameter of the ring is _____________mm. (α = 12 × 10–6
/°C)
298. In the inversion of raw sugar, the time rate change varies as the amount of raw sugar
remaining. After 10 hours, 8000 kg of sugar has been reduced to 800 kg. After 40 hours, the
amount of sugar will reduced to ____________ kg.
Which of the following reversed loading, having the same value of mean and variable stress,
will be most severe for the machine component
299. A journal bearing of a centrifugal pump has the following data:
Load on bearing = 20 kN, speed of journal = 900 rpm, viscosity of oil = 0.017 kg/ms. If the
diameter of the bearing is 100 mm and its length is 1.6 times the diameter, the bearing
modulus is:
Which of the following figures correctly represent the variation of bending stress and shear
stress (respectively) in a simply loaded I-section beam?
300. A rigid vessel of volume 1.2 m3 contains 2 kg of steam at a pressure of 2 bar. The
steam is heated to raise its pressure to 2.5 bar. The internal energy at the end of the process
(in kJ/kg) is Use the following table:
301. Air at 25°C flows past a flat plate of width 1 m at 5 m/s velocity. The plate is heated
over its entire length to a uniform temperature of 75°C. The drag force (on one side) exerted
on the first 50 cm length of the plate is ____________ × 10–3 N. The thermo-physical
properties of air are
302. Water flows at a rate of 170 L/s through a bend meter, shown below. The diameter of
the bend is 150 mm and pressure drop is 300 mm of Hg. Resistance coefficient of the bend
will be _________.
303. The overall heat transfer coefficient due to convection and radiation for a steam main
at 207°C running in a large room at 27°C is 18 W/m2K. The heat transfer coefficient due to
convection, taking emissivity of the pipe surface as 0.7 is __________ W/m2K.
304. In a steam power plant, heat is supplied to the feedwater at the rate of 2500 kJ/kg. The
exhaust steam gives up heat at the rate of 1000 kJ/kg. The steam rate through the plant is 4
kg/kWhr. If the generator efficiency is 90%, the thermal efficiency exceeds the brake thermal
efficiency by _________ percent.
305. Air enters an axial flow compressor at the rate of 25 kg/s. At the inlet of the first stage,
the stagnation pressure and temperature are 1 bar and 300 K respectively. If the power input
per stage of the compressor is 502.5 kW, then taking inentropic efficiency of 85%, the
number of stages required to deliver air at stagnation pressure of 4 bar is ___________.
306. A medium carbon steel workpiece is turned on a lathe at 50 m/min speed, 0.8 mm/rev
feed and 1.5 mm depth of cut. The rate of material removal is _________ mm3/min.
307. Air at 30°C is to be heated and humidified to 40°C DBT and 35°C WBT. It is made to
pass through an adiabatic humidifier followed by a heater having surface coil temperature
50°C and a bypass factor 0.4. If the WBT at the exit of humidifier is 20°C, the humidifying
efficiency is __________ percent.
308.
The value of a + b is ________
309. For a system with fixed order quantity, the following parameters for an item are given
Annual demand (D) = 50000 units, Unit cost = Rs. 2, Ordering cost = Rs. 15 per order,
Holding cost = 12% The past lead times are found to be 10 days, 20 days, 15 days, 15 days,
The re-order level is ___________ units. (Take number of working days in a year = 250)
310. During the testing of a 4 cylinder, 4 stroke IC engine, the following data was noted
Brake power = 45kW, Mechanical efficiency = 75%, Fuel consumption rate at stoichiometric
condition = 12.5 kg/hr, Equivalence ratio = 1.1, Calorific value of fuel = 45000 kJ/kg. The
indicated thermal efficiency of the engine is _____________ percent.
311. The residue of f (z) = is ______.
Consider the following statements:
1. For elastic materials, stress is a function of strain only.
2. For visco-elastic materials, stress depends not only on strain but also on the rate at which
the strain is applied. both 1 and 2
312. What is the reaction at C for the beam pin supported and A and roller supported at C
as shown in the figure ?
313. An involute spur gear having 4 mm module and 50 teeth is used to transmit 20 kW at
1200 rpm. Its face width is 20 mm and pressure angle of the tooth is 20°. The minimum
allowable stress for the gear material is 180 MPa. The factor which considers the combined
effect of pitch line velocity, inertia of rotating parts, dynamic load and other factors is 2.
What is the gear tooth form factor ?
Very slow motion of a sphere in a viscous fluid was first analysed by Sir George G. Stokes
on the assumption that the inertia forces are negligibly small as compared to the viscous
ones. The drag force resisting the motion of the sphere is given by
3πμVd
314. A closed cycle ideal gas turbine plant produces a maximum work of 200 kJ/kg. The
maximum temperature attained is 707°C. A fuel of calorific value 20000 kJ/kg is used. The
air fuel ratio is _______. (Assume cp = 1 kJ/kgK and ratio of specific heats = 1.4)
315. he general solution of the differential equation
316. A 4 cm diameter object spherical in shape, is initially at 25°C temperature. It is placed
in boiling water at 100°C for 30 seconds. The value of Biot number and Fourier’s number for
the process can be taken as 0.12 and 5.6 respectively. Assuming lumped heat capacity
method to be valid, the temperature of the object after 30 seconds is __________°C.
317. The branch of a bank has only one typist. The typing rate is randomly distributed
approximating a Poisson distribution with mean service rate of 9 letters per hour. The letters
arrive at a rate of 4 per hour during the entire 8-hour work day. If the typewriter is valued at
Rs. 1.50 per hour, the average cost due to waiting on the part of typewriter remaining idle is
Rs. __________.
318. The tolerance for the basic dimension in the nominal step of 30 mm to 50 mm and
IT9, is ________ μm.
319. A 100 mm diameter cutter having 8 teeth is cutting steel at 50 m/min. The depth of cut
is 5 mm and table feed rate is 150 mm/min. The width of the workpiece is 100 mm, then the
mean area of crosssection of the chip in a slab milling operation is ____________ mm2.
320. In a three wire inspection of external metric thread of M18 × 2, the measurement over
the wire was found to be 18.6 mm. The effective pitch diameter of the thread is ________
mm.
321. A close coiled helical spring made of round steel wire of diameter 8 mm is required to
carry a load of 1000 N. If the stiffness of the spring is 10 N/mm and diameter of helix is 80
mm then the number of turns required in the spring is ___________. (Take modulus of
rigidity of steel = 82 kN/mm2)
322. If A is a non-singular matrix and the eigen values of A are 0.5, 0.6 and 0.7, then the
maximum value of the eigen values of A–1 is _____
323. The scales are so chosen that a reversible cycle plots clockwise circle on the T-S
plane. The minimum and maximum values of the temperature are 305 K and 627 K and the
entropy 1.23 kJ/K and 2.85 kJ/K respectively. The cycle efficiency is
Consider the following statements:
S: Fluids that posses a linear relationship between shear stress and velocity gradients is called
Newtonian fluids.
T: A fluid where properties are independent of direction at a given position is called isotropic
fluid.
U: A fluid whose properties are independent of position is called homogenous fluid.
S, T and U are true
324. A bolted joint with 2 bolts each at top and bottom and of equal diameter is shown in
the figure below. The yield shear stress of the bolt material is 200 MPa. What is the diameter
of the bolts, if they are designed using maximum distortion energy theory of failure ?
325. What is the inclination of resultant stress with normal of plane of maximum shear
stress of 20 N/mm2 and resultant stress of 90 N/mm2?
where σ1 and σ2 are major and minor principal stresses respectively?
326. A gear pair consists of two spur wheels each having 40 teeth. The pressure angle is
20° and the circular pitch is 4 cm. If the gear pair is to maintain a minimum contact ratio of
1.5, what is the minimum addendum of the teeth?
327. he suspension system of a two-wheeler can be equated to a single spring mass system
with viscous damper connected in series. The mass and spring stiffness are 50 kg and 25
kN/m respectively. For the system to be critically damped, a force of 135 N is exerted. What
is the plunger velocity?
328. The thrust on the propeller shaft of an engine is beared by a number of collars of outer
diameter 60 cm integral with the shaft of diameter 45 cm. The shaft speed is 120 rpm. A
uniform pressure of 0.5 MPa acts on the collar with coefficient of friction 0.05. What is the
minimum number of collars required if the power loss due to friction is not to exceed 25 kW?
329. The strain on the surface of an experimental specimen made of pure aluminium (E =
70 GPa, μ = 0.33) were measured by means of strain gauges. The gauge were oriented as
shown in the figure and the measured strains were εA = 1100 × 10–6, εB = 1496 × 10–6, and εC
= – 39.44 × 10–6. The stress σx in the x-direction, is
330. A long metal tube, 7.5 cm internal diameter and 0.15 cm thick, has closed ends, and is
subjected to an internal fluid pressure of 3 MN/m2. If modulus of elasticity of tube is 200
GN/m2 and volumetric strain of tube is 0.727 × 10–3, then what is Poisson’s ratio?
331. Sixteen ice cubes, each with a temperature of –10°C and a volume of 8 mL, are added
to 1 L of water at 20°C in an insulated container. What is the equilibrium temperature?
Take, (cp)ice = 2.1 kJ/kgK; Latent heat of ice = 330 kJ/kg; Specific volume of ice at –10°C =
0.00109 m3/kg
332. The value of Integral I =
333. Saturated steam leaves a turbine at a flow rate of 2 kg/s and a pressure of 0.51 bar. The
vapor is to be completely conduced to saturated liquid in a shell and tube heat exchanger
which uses water as coolant. The water enters the thin walled tube at 15°C and leaves at
55°C. The overall heat transfer coefficient is 200 W/m2K. After extended operation, fouling
causes the overall heat transfer coefficient to decrease to 100 W/m2K. For the same water
inlet temperature and flow rate, the percentage reduction in vapour flow rate required for
complete condensation, due to fouling is __________ percent. Properties of water
334. A pressure gauge is installed in front of a valve on a water pipe of diameter is 50 mm.
When the valve is closed the gauge reads 6 bar. When the valve is opened, the reading drops
to 2 bar. The discharge of water in the pipeline is ________ litre/s.
335. A single slider crank mechanism based reciprocating engine is given. Line of
reciprocating of the slider passes through the centre of rotation of the crank shaft. The total
axial force on the piston is 2 kN. A torque is 100 Nm is produced on the crank shaft at the
instant when the connecting rod makes an angle of 10° with the line of stroke of piston and
the crank is 60° away from inner dead centre position. What is the length of the connecting
rod?
336. A venturimeter is to be fitted in a 150 mm diameter pipeline horizontally at a section
where the pressure is 100 kN/m2 and the pressure at the throat is 75 kN/m3 (vacuum). The
diameter of throat (in mm) is ___________. Assume that 3% of the differential head is lost
between the inlet and the throat.
337. A thin metal plate is exposed to solar radiation. The air and surroundings are at 25°C.
The heat transfer coefficient by free convection from upper surface of the plate is 15 W/m2K.
The plate has an absorptivity of 0.4 at the long wavelength. The incident solar radiation
intensity is 800 W/m2 and there is negligible
heat loss from lower surface. If the measured equilibrium temperature of plate is 60°C, the
absorptivity of the plate at solar wavelength is ________.
(Take Stiffen Boltzmann constant = 5.67 × 10–8 W/m2K4)
338. Consider a gas turbine that has a pressure ratio of 6 and operates on the Brayton cycle
with regeneration between the temperature limits of 20°C and 900°C. If the specific heat
ratio of the working fluid is 1.3, the highest thermal efficiency this gas turbine can have is
______%.
339. A steam turbine plant is supplied with steam at 240°C and superheated to 600°C. The
condenser is kept at 45°C. If the steam consumption rate is 3.27 kg/kWh, the boiler pressure
exceeds the condenser pressure by _____________ MPa.
340. A vapour compression refrigeration works between pressure limits of 10 bar and 3 bar.
The working fluid is dry at the end of compression and there is no undercooling before the
expansion valve. If refrigerant flow rate is 10 kg/min, the capacity of the refrigerator (in ton)
is ___________. Table for properties of the refrigerant as given below:
341. A stockiest has to supply 400 units of a product every Monday to his customers. He
gets the product at Rs. 50 per unit from the manufacturer who charges an ordering cost of Rs.
75 per order. The cost of carrying the inventory is Rs. 3.75 per unit per year. The total daily
profit if the item is sold for Rs. 55 per unit is Rs. _________. (Assume 52 week per year)
342. A carbon steel member is being machined at a cutting speed of 0.8 m/s with a tool
rake angle and width of cut is 5 mm and uncut chip thickness 0.25 mm respectively. The
average value of coefficient of friction between the tool and chip is 0.3 and the yield strength
of the material is 400 MPa. The force required for cutting is _________ N. (Assume Lee and
Shaffer’s relation)
343. A single cylinder CI engine with a brake thermal efficiency of 30% uses diesel oil
having a calorific value of 42000 kJ/kg. If mechanical efficiency of CI engine is 80%, the
brake specific fuel consumption (in kg/kWh) is __________.
344. The value of
Consider the following statements:
1. Strength of steel increases with carbon content.
2. Young’s modulus of steel increases with carbon content.
3. Young’s modulus of steel remains unchanged with variation of carbon content.
Choose the correct statement(s): 1 and 3
345. A journal bearing is loaded with a radial load of 30 kN. The journal diameter and
length both are 100 mm and it rotates at 1200 rpm. The heat is dissipated from the surface at
the rate of 96 J/m2/s/°C. The bearing housing is 20 times the projected area. If coefficient of
friction is 0.003 and room temperature is 35°C, then the surface temperature of the bearings
is
Across the runner of a reaction turbine,
relative velocity increases
346. A two stage reciprocating compressor has an inlet pressure of 1 bar and temperature
300 K. Air after first stage of compression is cooled to a temperature of 400K in an
intercooler, maintained at a pressure of 5 bar. What is the delivery pressure ?
347. At what point on the curve y = (cosx – 1) in (0, 2π), the tangent is parallel to x-axis?
348. The cost of holding an item in stock is Rs. 5 per unit and the shortage cost is Rs. 12. If
Rs. 4 is the purchasing cost per unit, the optimal level of inventory is ____________.
Given below is the probability distribution
349. In the welding process, output current for 25% duty cycle is 220 amp, then the weld
output current for 55% duty cycle is __________amp.
350. A mild steel block of width 25 mm is being milled using a straight slab cutter 80 mm
diameter with 20 teeth. If the cutter rotates at 35 rpm and depth of cut is 2 mm. When the
table feed is 20 mm/min, the value of maximum uncut chip thickness, is ________ μm.
351. An open coiled helical spring with α = 45° is subjected to an axial load W such that
shear stress due to twisting moment is 100 MPa, then the bearing stress due to bending
moments is _________ MPa.
Consider the following statements related to Taylor’s principle:
1. Taylor’s principle can be used for holes and maximum diameter of hole should not exceed
the ‘NoGo’ limit of size.
2. Taylor’s principle cannot be used for shafts.
3. Taylor’s principle can be used for shafts and minimum diameter of shaft should not be less
than ‘NoGo’ limit of size. 1 and 3
352. A steel drive shaft of 100 mm diameter is transmitting 200 kW at 600 rpm to a
machine having same diameter shaft with a CI flange coupling. The permissible shear stress
for shaft, bolt and key are 50 MPa, 40 MPa and 30 MPa respectively. The bearing stress for
bolt and key are 50 MPa. If the width of the key is 50 mm, what is its thickness?
353. The turning moment diagram of an engine is shown below:
The speed of the wheel varies between 300 rpm and 360 rpm. What is the crank angle
measured from TDC, when the angular acceleration of the wheel is 92.15 rad/s2?
354. A hydrodynamic bearing supporting a load of 12 kN, has a length of 80 mm. It runs at
a speed of 1200 rpm. The radial clearance is 0.05 mm and the minimum oil thickness is 0.01
mm. The viscosity of oil used is 0.30 m Pa-s. If the Sommerfeld number is 0.056, the journal
diameter (in mm) is
355. A vibrating system consists of a mass 8 kg, connected to a spring of stiffness 300 N/m
and a damper. After 3 cycles, due to damping, the original amplitude is reduced by 80
percent. What is the damping coefficient of the damper (in N-s/m)?
356. An aluminium alloy rod of diameter 12 mm and length 150 mm is subjected to a
tensile load of 30 kN along its axis. The Young’s modulus and Poisson’s ratio for aluminium
are 60 GPa and 0.3 respectively.
The elastic energy per unit volume is approximately (MJ/m3):
A simply supported beam has the square cross-section having moment of inertia 1728 mm4. It
carries a uniformly distributed load of intensity 10 N/m. Considering only the top fibre of the
beam, the correct representation of the longitudinal variation of the bending stress is
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