Revisi Cepat SPM Physics Form 4 & 5

Coloured Graphical Notes

Physics

FORM

Norhafizan binti Abdul Wahab
(Guru Cemerlang)
Noor Irina binti Muharam
Ahmad Izzauddin Shah bin Ibrahim
Lim Kim Liang

Form 4 i-THINK Tree Map Form 4

Chapter 1 Measurement
Base Quantities and Derived Quantities

Physical quantities

Base quantities Derived quantities

• Cannot be derived from other • Derived from base quantities
physical quantities through multiplication and/or
division
• Example: Length, mass,
temperature, time, current, • Example: Speed, force, area,
luminous intensity, amount of volume
substance

Scalar Quantities and Vector Quantities i-THINK Tree Map
Physical quantities

Scalar quantity Vector quantity
• Has magnitude only • Has magnitude and direction
• Examples: Distance, speed • Examples: Velocity, acceleration

N1

Interference of Waves

The distance between Wave i-THINK Multi-Flow Map
two coherent sources,
interference The distance between
a, increases ax two antinodal lines,
λ = D
The wavelength of the x decreases
Form 4 wave, λ increases
The distance between
The distance between two antinodal lines,
coherent sources and
x increases
screen increases
The distance between
Electromagnetic Spectrum two antinodal lines,

x increases

Increasing wavelength

Wavelength Radio Microwave Infrared Visible Ultraviolet X-ray Gamma ray
(metre) wave 10–1 ray light 10–8 10–11
104
ray
10–6 10–7
10–4

About the
size of
Buildings Honey Protozoans Molecules Atoms Atomic
Humans bee Pinpoint nuclei

Frequency 104 108 1012 1015 1016 1018 1020
(Hz)

Increasing frequency

Chapter 6 Light and Optics i-THINK Multi-Flow Map
Total Internal Reflection
Refracted away
Incident angle, Light ray travels from normal
i Ͻ critical angle, c from less dense
Refracted with
i=c into denser refracted angle,
medium
iϾc r = 90°

Total internal
reflection occurs

N14

Chapter 7 Quantum Physics
Photoelectric Effect

The emitted photoelectrons are attracted to the anode.

The movement Light Photocell Light sensitive When a light
of the source e metal sensitive metal
photoelectrons e is shone with
from cathode 1 e 2 certain light
to the anode beam,
produces a Anode mA photoelectrons
current which Vacuum 3 will be emitted
is recorded by a from the metal
milliammeter. surface.

Characteristic of Photoelectric Effect

Form 5 The higher the frequency of light, The kinetic energy of photoelectrons does
the higher the kinetic energy of not depend on the intensity of light

emitted electrons Photoelectrons are emitted

There is minimum instantaneously when light
shines on a metal surface
frequency of light Characteristics
needed for a metal to of photoelectric
emit electrons called effect Photoelectrons are emitted
with maximum kinetic
energy, Kmax = hf – hfo
threshold frequency

Work Function and Threshold Frequency for Photoelectric Effect

Work function, W Threshold frequency, fo
The minimum energy required The minimum frequency for a
for an electron to be emitted light photon to produce
form a metal surface photoelectric effect

W = hfo

The relationship between the threshold frequency of a metal and work function

Kmax When light frequency exceeds threshold frequency,
the emitted electrons will acquire kinetic energy.
The kinetic energy increases with frequency.

O fo f • The higher the threshold frequency of a
W = hfo metal, the higher the work function

• Different metals have different threshold
frequencies

N32

Contents

Graphical Notes N1 – N32 Theme 3: Heat

Form 4 Chapter Heat 83

4 83
88
Theme 1: Elementary Physics 4.1 Thermal Equilibrium 95
4.2 Specific Heat Capacity 103
Chapter Measurement 1 4.3 Specific Latent Heat 112
4.4 Gas Laws
1 1 Summative Practice 4
4
1.1 Physical Quantities 14
1.2 Scientific Investigation
Summative Practice 1

Theme 4: Waves, Light and Optics

Theme 2: Newtonian Mechanics Chapter Waves 114

Chapter Force and Motion I 16 5

2 5.1 Fundamentals of Waves 114
5.2 Damping and Resonance 123
2.1 Linear Motion 16 5.3 Reflection of Waves 126
2.2 Linear Motion Graphs 29 5.4 Refraction of Waves 131
2.3 Free Fall Motion 39 5.5 Diffraction of Waves 135
2.4 Inertia 43 5.6 Interference of Waves 140
2.5 Momentum 47 5.7 Electromagnetic Waves 146
2.6 Force 52 Summative Practice 5 149
2.7 Impulse and Impulsive Force 56
2.8 Weight 58
Summative Practice 2 60

Chapter Light and Optics 151

6

Chapter Gravitation 63 6.1 Refraction of Light 151

3 63 6.2 Total Internal Reflection 158
73
3.1 Newton’s Universal Law of 76 6.3 Image Formation by Lenses 163
Gravitation 81
6.4 Thin Lens Formula 169
3.2 Kepler’s Laws
3.3 Man-made Satellites 6.5 Optical Instruments 172

Summative Practice 3 6.6 Image Formation by Spherical

Mirrors 176

Summative Practice 6 184

1Chapter Theme 1: Elementary Physics

Measurement

1.1 Physical Quantities 8 The metric system is convenient CHAPTER 1 FORM 4
for calculation because the units
1 Physical quantities are quantities are based upon factors of 10.
that can be measured.
9 S.I. units (International System
2 Measurement of physical of Units) have become the
quantities are expressed in terms fundamental basis of scientific
of unit. measurements.

3 Units are standardised values for 10 Physical quantities can be
any measurements of the same classified into base quantities
physical quantities. and derived quantities.

4 There are two major systems of Base Quantities and Derived
units used in the world: imperial
(British) system and metric (S.I.) Quantities
system.
1 Base quantities are physical
5 The imperial system consists of quantities that cannot be
units such as inch, foot, yard, defined in terms of other physical
mile, gallon, pint, ounce, pound quantities.
and stone.
2 Table 1.2 shows the seven base
6 The metric system uses the quantities and their respective S.I.
measuring units such as metres, units.
grams and litres, and prefixes
are added to count the order of Table 1.2 Base quantities and their S.I. units
magnitude.
Base quantity S.I. unit
7 Table 1.1 shows some commonly
used metric and imperial units. Name Symbol Name Symbol

Table 1.1 Metric units versus imperial units Length l metre m

Physical Metric Imperial Mass m kilogram kg
quantity units units
Time t second s

Length millimetre, inch, foot, Thermodynamic T kelvin K
centimetre, yard, mile temperature

metre, Electric current I ampere A
kilometre

Mass milligram, ounce, Luminous Iv candela cd
gram, pound, intensity
stone
kilogram Amount of
substance
Volume millilitre, pint, n mole mol
litre gallon

1

3 All physical quantities other than 4 Derived quantities are physical
the seven base quantities are quantities that are derived by
derived quantities. combining base quantities
through multiplication or division
Memorise all seven base quantities and or both.
their respective S.I. units; the others are
derived quantities. 5 Table 1.3 shows some derived
quantities expressed in base
quantities and their units.

CHAPTER 1 FORM 4 Table 1.3 Derived quantities, their relationships with base quantities and units

Derived Symbol Formula Expressed in base Derived unit
quantity quantities

Volume V V = l3 l×l×l m3
Speed v m s–1
Density ρ v= l l kg m–3
Acceleration a t t m s–2
Momentum p kg m s–1
Force F ρ = m m kg m s–2
Pressure P V l×l×l kg m–1 s–2
Work W kg m2 s–2
a= v l
t t×t
m×l
p = mv
t
F = ma
m×l
P = F t×t
A
m
W = Fl l×t×t
m×l×l

t×t

EXAMPLE

Derive the units for the following physical quantities.
(a) Area
(b) Momentum

Solution:

(a) Expressed in base quantities, area = l × l
Expressed in base units, unit of area = m × m = m2

(b) Expressed in base quantities, momentum = m×l
t

Expressed in base units, unit of momentum = kg × m = kg m s–1
s

2

EXAMPLE

A student carried out an experiment to study the relationship between force exerted, F
and extension of spring, x. A graph of F against x is plotted as shown in Diagram 1.4.

F (N) Based on the graph: CHAPTER 1 FORM 4
(a) State the relationship between F
16 x (cm)
14 and x.
12 (b) Determine the gradient of the
10
graph, k.
8 (c) What is the physical quantity
6
4 represented by the gradient?
2 (d) Determine the area under the

0 12345 graph.
(e) What is the physical quantity

represented by the area under
the graph?
(f ) What is the extension of the
spring when the force exerted is
10 N?
(g) What happens to the extension
of the spring when the force
exerted is 20 N?

Diagram 1.4

Solution: (e) Area under the graph
(a) F is directly proportional to x.
= 1 Fx
2
15 – 0
(b) k= 5–0 = 3 N cm–1 = Work done to stretch the spring

(f ) 3.3 N

Unit of gradient must be stated.

(c) Gradient = Force, F Draw a horizontal line at 10 N on
Extension of spring, x the graph. Then, draw a vertical
line to the x-axis.
= Spring constant, k (g) More than 5 cm

(d) 1 × 5 × 15 = 37.5 N cm
2

Unit of area under the graph must Extend the graph to get prediction.
be stated.

7

EXAMPLE

A car accelerates at 4 m s–2 from an initial velocity of 5 m s–1 for 10 seconds. What is the
distance travelled by the car?

Solution:

Acceleration, a = 4 m s–2 List down all the information, then
select the suitable formula that
Initial velocity, u = 5 m s–1 involves the four variables.

Time taken, t = 10 s a, u, t and s are involved, use
equation ᕣ to solve the problem.
CHAPTER 2 FORM 4 Displacement, s = ?

s = ut + 1 at 2
2
1
= (5)(10) + 2 (4)(10)2

= 250 m

EXAMPLE

A truck accelerates from 4 m s–1 and reaches a velocity of 28 m s–1 after travelling for
64 m. What is the acceleration of the truck?

Solution: List down all the information that
Initial velocity, u = 4 m s–1 is given.
Final velocity, v = 28 m s–1
Displacement, s = 64 m u, v, s and a are involved, use
Acceleration, a = ? equation ᕤ to solve the problem.

v2 = u2 + 2as
282 = 42 + 2a(64)

a = 6 m s–2

QUICK CHECK 2.1

1 Define the meaning of (a) displacement, (b) velocity, and (c) acceleration.

2 In a long jump event, Johan was running at a velocity of 4 m s–1 towards a long jump
pit. He needed to reach 9 m s–1 after covering a distance of 4.0 m before lifting the
ground from the jumping board.
(a) Calculate the required acceleration for Johan to do so.
(b) Calculate the time taken to cover the distance of 4.0 m.

3 A bus accelerates with an acceleration of 3.0 m s–2 after picking some students at a
bus stop. Calculate the
(a) velocity after 10 s, (b) distance travelled after 5 s.

4 In a school activity, Hafiz walks 10 m due north. Then, he reverses the direction and
walks 8 m. Finally, he reverses his direction and walks another 12 m. If the time taken
is 20 s, what are his speed and velocity?

5 By applying the brakes, a car driver decelerates his car from 20 m s–1 to 10 m s–1 after
a distance of 30 m. Calculate the deceleration of the car.

28

Analysing Displacement-Time Graph to Determine Distance, Displacement and
Velocity
1 Diagram 2.29 shows the displacement-time graph for the linear motion of a

bicycle. The bicycle is pedalled to the right and then to the left.

Displacement, s (m)

50 B C

CHAPTER 2 FORM 4 A DE

0 5 10 15 16 20 25 Time, t (s)

-40 F

Diagram 2.29 A displacement-time graph of a bicycle

2 Each segment of the displacement-time graph is analysed. The motion of the
bicycle is described in Table 2.5.

Table 2.5 Analysis of the displacement-time graph

Segment Motion of bicycle
AB
BC The bicycle travels 50 m to the right for 5 seconds.
CD
DE Velocity = Gradient of graph = 50 – 0 = 50 = 10 m s–1
EF 5–0 5

Therefore, the bicycle travels at a velocity of 10 m s–1 to the right.

The bicycle stops for 5 seconds.
Velocity = Gradient of graph = 0 m s–1

The bicycle travels back 50 m to initial point in 6 seconds.

Velocity = Gradient of graph = 0 – 50 = –50 = –8.33 m s–1
16 – 10 6

Therefore, the bicycle travels at a velocity of 8.33 m s–1 to the left.

The bicycle stops at initial point for 4 seconds.
Velocity = Gradient of graph = 0 m s–1

The bicycle travels 40 m to the left for 5 seconds.

Velocity = Gradient of graph = –40 – 0 = –40 = –8 m s–1
25 – 20 5

Therefore, the bicycle travels at a velocity of 8 m s–1 to the left.

34

Experiment 2.1

Aim: Procedure: CHAPTER 2 FORM 4
To measure the Earth’s gravitational 1 The apparatus is set up as shown in
acceleration
Diagram 2.40.
Apparatus and materials: 2 The second photogate is placed so
Photogate system and electronic timer,
electromagnetic release, steel ball and that the distance is 30.0 cm away
container to catch steel ball released. from the first photogate.
3 The steel ball is ensured can fall
Arrangement of apparatus: through both photogates into the
container.
Electromagnetic Steel ball 4 The steel ball is released from the
release First photogate electromagnetic release.
5 The time when the steel ball passes
Second photogate through the first photogate, t1 and
the second photogate, t2 is recorded
Electronic Container to catch in Table 2.8.
timer steel ball 6 Steps 3 to 6 are repeated with
distances 40.0 cm, 50.0 cm, 60.0 cm
Tripod stand and 70.0 cm.

Diagram 2.40

Results: Table 2.8

Distance Time when the steel Time when the steel Gravitational
between two ball passes through ball passes through acceleration,
photogates, the first photogate, the second photogate,
g (m s–2)
h (cm) t1 (s) t2 (s)
30.0
40.0
50.0
60.0
70.0

Analysis of data: Discussion:
1 The value of g also can be determined
1 The values of g are determined
2h by using ticker timer and ticker tape
using the formula, g = t22 – t12 . but the value is less accurate.
2 The value of g changes from one
2 The average value of g is calculated. place to another because Earth is not
a perfect sphere.
Conclusion: 3 To improve the accuracy of the results
The Earth’s gravitational acceleration is in this experiment, switch off the fan
9.81 m s–2. to reduce air friction.

41

Effects of Inertia in Daily Life
1 Daily life situations that involve inertia and its effects are as follows:

Chilli sauce can be easily come out The head of a hammer is fit tightly to
from the bottle if the bottle is moved its handle by knocking one end of the
downwards fast and stopped suddenly. handle vertically on a hard surface.

CHAPTER 2 FORM 4 The inertia causes the chilli sauce to When the handle hits on the surface,
keep on moving downwards and out the handle stops but the head keeps on
of the bottle. moving downwards due to the effect of
Raindrops on an umbrella can be inertia. As a result, the head fits tighter
removed by spinning the umbrella. into the handle.
When entering a building through a
revolving door, inertia will allow the door
to hit you in the back if you do not get
out of the way.

When the direction of the umbrella When a bus stops, the driver and
changes, the raindrops keep moving passengers in the bus may feel as their
forwards due to the effect of inertia. As bodies are moving forwards.
a result, the raindrops leave the surface
of the umbrella.
When a bus abruptly accelerates, the
driver and passengers may feel as if
their bodies are moving backwards.

Their bodies tend to maintain their The effect of inertia causes their body to
state of motion due to the effect of keep moving forwards. As a result, the
inertia. As a result, the driver and passengers are thrown forwards.
passengers are thrown backwards.

Diagram 2.47 Examples of situations that involve inertia

46

EXAMPLE QUICK CHECK 2.5

A policeman fires a pistol which has a 1 A ball with a mass of 0.8 kg strikes
mass of 2.0 kg. If the mass of the bullet a wall at a velocity of 10 m s–1 and
is 10 g and it reaches a velocity of rebounds at 6 m s–1. What is the
200 m s–1 after shooting, what is the momentum before striking the wall
recoil velocity of the pistol? and after the rebound?

Solution: 2 A cannon ball with a mass of 5 kg is
fired from a cannon with a mass of
CHAPTER 2 FORM 4 m1 = 2.0 kg, m2 = 0.01 kg, u1 = 0 m s–1, 600 kg at a speed of 40 m s–1. Find
the recoil velocity of the cannon.
u2 = 0 m s–1, v2 = 200 m s–1, v1 = ?
3 Ali and his younger brother, Abu are
According to the Principle of at an ice rink.
Conservation of Momentum, Abu with a mass of 20 kg is moving
0 = m1v1 + m2v2 at a velocity of 2 m s–1 while Ali with
a mass of 50 kg, is directly behind
0 = (2.0)v1 + (0.01)(200) Abu and moving at 6 m s–1. Ali picks
–2.0 up Abu and continues moving.
v1 = 2.0
Ali Abu
= –1 m s–1

∴ Recoil velocity of the pistol is 1 m s–1.

Negative value means the direction Diagram 2.53
of the pistol is opposite to the
direction of the bullet. (a) Name the type of collision in the
above situation.
10 When firemen use water to put
out a fire, it often takes two (b) Determine the final velocity of
or more people to hold the Ali and Abu.
hose. A large volume of water
rushes out of the hose at high (c) State an assumption that you
speed possesses a large forward have made in 3(b).
momentum. To conserve that
momentum, the hose recoils and 2.6 Force
may cause the firemen to move
backwards. As a result, they need 1 Force and momentum are related.
to hold the hose tightly. 2 Force is push or pull that is

Diagram 2.52 Firemen putting out a fire exerted on an object to change its
momentum.
3 Force is a vector quantity that has
magnitude and direction.
4 The unit for force is Newton, N.
5 Force can cause an object with a
mass to change its velocity.

52

Activity 2.4

Aim: Apparatus and materials: CHAPTER 2 FORM 4
To investigate the relationship Ticker timer, alternating current power
between force and acceleration and supply, runway, three trolleys, retort
the relationship between mass and stand, ticker tape, cellophane tape and
acceleration three elastic strings with a knotted loop
at each end.
Arrangement of apparatus:

Ticker Ticker Retort stands
tape timer Elastic string

12 V a.c. Trolley Friction compensated
power Diagram 2.54 runway
supply

A Relationship between force and 3 The acceleration of the trolley is
acceleration with a fixed mass calculated using the ticker tape
obtained and is recorded in Table
Procedure: 2.13.

1 The apparatus is set up as shown in 4 Steps 2 to 3 are repeated using
Diagram 2.54. two elastic strings and three elastic
strings with each of the strings
2 The ticker timer is switched on stretched to the same length as that
and the trolley is pulled down the of the first elastic string in step 2.
runway by an elastic string (one
unit of force). 5 The graph of acceleration, a against
force, F is plotted.

Results:

Table 2.13

Force, F u (cm s–1) v (cm s–1) t (s) a (cm s–2)

1 elastic string

2 elastic strings

3 elastic strings

B Relationship between mass and 2 Step 1 in B is repeated using two
acceleration at a constant force trolleys and then three trolleys.

Procedure: 3 The acceleration of the trolley is
1 Steps 1 and 2 in A are repeated by calculated from the ticker tape
obtained and is recorded in Table
pulling the trolley using two elastic 2.14.
strings stretched together. 4 The graph of acceleration, a against

reciprocal of mass, 1 is plotted.
m

53

Summative Practice 2

CHAPTER 2 FORM 4 Answer all questions. 3 Diagram 3 shows the graph of
velocity against time for a car.
1 Diagram 1 shows a section of
ticker tape which recorded the v (m s–1)
motion of a trolley.
0 t (s)
XY
Diagram 3
Direction of motion
Which graph is the variation of
Diagram 1 the displacements, s, of the car
with time, t?
Which statement is correct? AC

HOTS Analysing ss

A The velocity at Y is higher than 0 t0 t
at X
BD
B The frequency at X is higher
than at Y ss

C The acceleration at X is higher
than at Y

D The time interval at Y is longer
than at X

2 Diagram 2 shows a graph of
velocity against time for the
motion of a car.

v (m s–1)

0 t0 t

30 4 Diagram 4 shows the motion of a
toy car.

v (m s–1)

0 10 t (s) 4
3
Diagram 2 2
1
How far did the car travel before it t (s)
0
reaches a uniform velocity? –1 1 2 3 4 5 6 7 8 9 10

A 10 m Diagram 4

B 30 m Which statement is false?
A The acceleration of the toy car
C 150 m
D 300 m at the 7th second is 0

60

Dynamic Info

Two objects of the same materials but different masses may have the same amount of
heat but different temperatures and vice versa.

Table 4.2 Differences between heat and temperature

Heat Temperature CHAPTER 4 FORM 4
Heat is a form of energy so it has the Temperature indicates the thermal
capacity for doing work condition of an object
Heat is the cause Temperature is the effect
Heat is the total kinetic energy of the Temperature is the average kinetic energy
molecules of an object per molecule of an object
Heat contents of an object do not decide Temperature of an object decides the
the direction of heat flow from the object direction of heat flow from the object
S.I. unit of heat is joule (J) S.I. unit of temperature is kelvin (K)

5 Diagram 4.4 shows examples of applications of thermal equilibrium in daily
life.

Oven Refrigerator
When food is put in the refrigerator, the
heat from the food is transferred into
the air of the refrigerator. This process
will continue until thermal equilibrium
is achieved. The temperature of the
food is equal to the temperature of the
air in the refrigerator.

When food such as chicken is put in
the oven, the heat from the oven is
transferred into the food. This process
will continue until thermal equilibrium
is achieved. The temperature of the food
is equal to the temperature of the air in
the oven.

Clinical thermometer

When a clinical thermometer is placed in
contact with the body of a patient, the heat
from the body is transferred to the clinical
thermometer. If the body of the patient
and the clinical thermometer have reached
thermal equilibrium, then the temperature of
the clinical thermometer is the same as the
body temperature.

Diagram 4.4 Applications of thermal equilibrium in daily life

85

CHAPTER 4 FORM 4 shell which has a high specific air resistance when entering the
heat capacity and low thermal Earth’s atmosphere.
conductivity materials.
3 This can reduce the absorption 2 This friction increases the
of heat from the surroundings, temperature and causes the space
thus the temperature inside the capsule to burn.
building is reduced.
3 Therefore, the outer layer of a
Outer layer of space capsule space capsule is made from a
substance with a high specific
1 A space capsule on its journey heat capacity and high melting
back to Earth experiences high point.

Solving Problems Involving Specific Heat Capacity

EXAMPLE

An immersion heater of power 500 W is used to heat up 1 kg of water. Determine the
time taken to heat the water from 30 °C to 65 °C.
[Specific heat capacity of water = 4.20 × 103 J kg–1 °C–1]

Solution:

Given P = 500 W, m = 1 kg, ∆θ = (65 – 30) °C, t = ?

Electrical energy supplied to the heater = heat energy absorbed by the water

Pt = mc∆θ
mc∆θ
t = P

= (1)(4.20 × 103)(65 – 30)
500

= 294 s

Assumption: No heat is lost to the surroundings.

EXAMPLE

A metal block with a mass of 1 kg at initial temperature 35 °C is heated by a 12 V, 48 W
immersion heater for 10 minutes. If the final temperature is 90 °C, calculate the specific
heat capacity of the metal block.

Solution:

Given m = 1 kg, P = 48 W, t = 10 minutes, ∆θ = (90 – 35) °C, c = ?

Electrical energy supplied to the heater = heat energy absorbed by metal block

Pt = mc∆θ

c = Pt
m∆θ

= (48)(10 × 60) Unit of heating time needs
(1)(90 – 35) to change to seconds.

= 524 J kg–1 °C–1

94

3 Gay-Lussac’s law states that the Solving Problems Involving Pressure,
pressure of a fixed mass of gas Temperature and Volume of a Fixed
is directly proportional to the Mass of Gas Using Formulae from
absolute temperature of the gas at the Gas Laws
constant volume.

P∝T EXAMPLE

P = kT, k is constant A fish releases an air bubble of volume
2 cm³ at the bottom of a lake. The depth
CHAPTER 4 FORM 4 P =k of the lake is 10 m. Find the volume
T of the air bubble when it reaches the
surface of the lake. (Assume that the
where T = absolute temperature (K) atmospheric pressure is equal to 10 m
of water)
P = pressure of gas (Pa)

4 If a fixed mass of gas with initial

pressure, V1 and initial absolute Solution:

temperature, T1, then Vw1a=te2r, cm³, ?P1 = 20 m water, P2 = 10 m
P1 V2 =
T1 =k
Using equation,
and if its final pressure, P2 and
final absolute temperature, P1V1 = P2V2

T2 with its pressure remains (20)(2) = (10)V2
constant, then
V2 = 4 cm³
P2 =k ∴ Volume of the air bubble is 4 cm3.
T2

therefore, according to Gay-

Lussac’s law, EXAMPLE

P1 = P2 An iron cylinder containing a gas at a
T1 T2 pressure of 150 kPa when it is kept at a
room temperature of 27 °C. What is the
Scan QR or visit https://chem. pressure of the gas when the cylinder is
libretexts.org/Bookshelves/ placed outdoors where the temperature
General_Chemistry/Book%3A_ is 37 °C?
ChemPRIME_(Moore_et_
al.)/09%3A_Gases/9.09%3A_Gay- Solution:
Lussac's_Law to watch a video to
show that it may be dangerous to P1 = 200 kPa, T1 = (273 + 27) = 300 K,
heat a gas in a closed container. T2 = (273 + 37) = 310 K, P2 = ?

For educational purposes only Using equation,

Scan QR code or visit P1 = P2
https://www.youtube.com/ T1 T2
watch?v=QhnlyHV8evY to watch
a video to understand gas laws. 200 000 = P2
300 310
For educational purposes only
P2 = 207 kPa
∴ Pressure of the gas is 207 kPa.

Keywords
• Absolute temperature – Suhu mutiak

110

Scan QR code or visit Mechanical and electromagnetic CHAPTER 5 FORM 4
https://www.youtube.com/ waves
watch?v=6sgI7S_G-XI to watch
the vibration of a guitar string. 1 Mechanical waves require a
medium to transfer energy
For educational purposes only from one point to another. For
example, sound waves move
9 The stationary wave remains in through the air, and ripples in a
a constant position as a result of puddle move through water.
a combination of two identical
waves propagating in opposite 2 Electromagnetic waves do not
directions. require a medium to transfer
energy. For example, light from
10 Stationary waves can also be the Sun that reaches the Earth
produced when other musical and radio waves that propagate
instruments such as flute and signals on AM radio.
drum, are being played.
Double Bubble Map

Made up of Made up of
vibrating particles oscillating electric
and magnetic fields
of a medium perpendicular to

one another

Require a Mechanical Transfer Electromagnetic Do not require
medium to waves energy waves a medium to
propagate
propagate

Examples: water Examples: light
waves, sound waves, radio
waves, seismic waves
waves

Diagram 5.6 Comparison between mechanical and electromagnetic waves

Keywords • Electromagnetic wave – Gelombang elektromagnet
• Mechanical wave – Gelombang mekanik
117

CHAPTER 5 FORM 4 Effects of Resonance in Daily Life and the desired station can be
heard.
1 A crystal glass shatters when a
highly trained singer singing 4 In a musical instrument, such
a note that corresponds to the as drum, the whole instrument
natural frequency of the glass. As vibrates in response to sound
the sound wave is directed to the waves when the head of the drum
glass, it responds by resonating at is struck. The musical instrument
the same frequency as the sound uses resonance to amplify the
wave. The transfer of energy can sound and make the sound
overload the glass, causing it to louder.
vibrate and eventually shatter.
5 Washing machine and buses will
2 The Tacoma Narrows Bridge often vibrate violently when the
in USA collapsed in 1940. The engines oscillate at their natural
strong winds drove the bridge frequency.
into oscillations at its resonant
frequency causing the bridge to QUICK CHECK 5.2
twist and crumble. The bridge
writhed and buckled until it 1 A system is oscillating at its natural
collapsed into the water. The frequency in air.
Millennium Bridge in London was (a) What happens to the
closed for a short period of time amplitude after two hours?
for the same reason. (b) Give a reason for your answer
in 1(a).
Scan QR code or visit https://
www. youtube.com/watch?v 2 What is meant by forced oscillations?
=XggxeuFDaDU to watch the
effect of resonance on the 3 Resonance occurs when the external
Tacoma Narrows Bridge in 1940.
frequency is to the
For educational purposes only natural frequency of an oscillating
system and the system will oscillate
Dynamic Info
with .
The incident of the Tacoma Narrows
Bridge led to increase research 5.3 Reflection of Waves
and progress in understanding
aerodynamics, harmonic motion and 1 Reflection of waves occurs when
resonance. incident waves hit a reflector and
bounce back.
3 When selecting channels on
a radio or television, we are 2 The direction of propagation
adjusting the natural frequency of the waves changes when it is
of the electrical circuit of the reflected.
receiver so that it is equal to
the transmission frequency of 3 The wavelength, frequency and
the desired radio station. When speed of waves remain unchanged.
the two frequencies match, the
transfer of energy is maximum 4 The phenomenon of reflection of
waves can be studied by using a
ripple tank and its accessories.

126

Dynamic Info

Patterns of diffracted water waves after passing through obstacles of different sizes.

Small obstacle Large obstacle CHAPTER 5 FORM 4

Diagram 5.40 Spreading of waves is less significant at a large obstacle

Applications of Diffraction of Waves in Daily Life

Water waves Light waves Sound waves
Ocean waves passing The recording of a Animals such as whales,
through a gap between hologram on a credit rhinoceros and elephants
two concrete barriers are card involves the e ects can communicate
di racted and spread of di raction of light. over long distances by
throughout the bay. Their In order to reconstruct producing infrasonic
amplitude is smaller an image of the object, waves. The sound waves
compared with the a light is di racted by bend around obstacles
incident waves. Hence, plane surfaces within the such as plants and land
the bay is calm and safe hologram. The image with features in their habitat,
for docking of ships all of its three-dimensional and travel towards their
and water recreational details can be viewed by intended animals.
activities. observers.

Photograph 5.3 Examples of diffraction of water, light and sound waves

QUICK CHECK 5.5

1 Compare the diffracted waves with the incident waves in terms of

(a) Frequency (b) Wavelength (c) Speed (d) Amplitude

2 Ali was walking near an open window of his bedroom. He can hear the music from
the television outside the room.
(a) Explain why he can hear the music inside his bedroom.
(b) Name the phenomenon that occurs.

3 Diffraction of waves is the of waves when they move through an
opening or an obstacle.

139

5.6 Interference of Waves

Principle of Superposition of Waves

1. The principle of superposition states that when two or more waves meet at
a point, the resultant displacement at that point is equal to the sum of the
individual displacements of the waves.

CHAPTER 5 FORM 4 Wave 1 Wave 2

+A +A –A –A

Wave 1 Wave 2

+2A –2A

Diagram 5.41 Superposition of waves

Dynamic Info

The principle of superposition of waves applies to any number of waves, but to simplify
matters, we just consider what happens when two waves meet.

2 Interference of waves is the effect of superposition of two coherent waves.
3 Coherent waves refer to waves that have the same frequency and the

constant phase difference.
4 There are two types of interference of waves: constructive and destructive.
5 Constructive interference occurs when two crests or two troughs are in

superposition.

+A Before –A –A
+A superposition

+2A During –2A
superposition

+A After –A –A
+A superposition

Diagram 5.42 The superposition of two crests or two troughs of waves produces maximum amplitude

140

Answers

FORM 4 4 (a) y is independent of x
(b) y is inversely proportional to x
1Chapter Measurement (c) y increases linearly with x
(d) y decreases linearly with x
Quick Check 1.1
1 Energy – J, Force – N Summative Practice 1

2 Scalar quantity Vector quantity 1D 2D 3 C 4C 5C
6 B 7 B 8 A 9 D 10 C

distance velocity

mass weight Chapter Force and Motion I

time force 2

area Quick Check 2.1

3 Base quantity Derived quantity 1 (a) Distance at a specified direction
(b) Rate of change of displacement
time friction force (c) Rate of change of velocity
mass velocity

Quick Check 1.2 2 (a) u = 4 m s–1, v = 9 m s–1, s = 4.0 m, a = ?

1 (a) Inference is a nearly conclusion that v2 = u2 + 2as
you draw from an observation.
92 = 42 + 2(a)(4)
(b) Hypothesis is a statement to state
the relationship between two a = 8.125 m s-2
measurable variables that can be
investigated in a lab. (b) u = 4 m s–1, v = 9 m s–1, s = 4.0 m
1
(c) Variable is a quantity that can vary s = 2 (u + v)t
in value.
4= 1 (4 + 9)t
2 (a) The extension of spring depends on 2
the mass of object. t = 0.62 s

(b) If the mass of load increases, then 3 (a) a = 3.0 m s–2, u = 0, t = 10 s, v = ?
the extension of spring increases.
v = u + at
(c) Manipulated variable: Mass of load 1
v = 0 + 2 (3)(10)
Responding variable: Extension of
spring = 15 m s–1 ANSWERS

Constant variable: Spring constant (b) t = 5 s, s = ?
of spring 1
s = ut + 2 at2
3 Manipulated variables – Factors which
are changed in an experiment. = (0)(5) + 1 (3)(5)2
2
Responding variables – Factors which = 37.5 m
depend on the manipulated variables.
4 Speed, v = (10 +8+ 12)
Constant variables – Factors which 20
are kept the same throughout an = 1.5 m s–1
experiment.
Velocity, v= (10 – 8 + 12)
20
= 0.7 m s–1

365