CHICHA BAGU . HATIMI MUDIN POLYTECHNIC EDITION Consist of : Practical Experiment DIY Experiment Virtual Laboratory
FLUID MECHANICS Laboratory Experiments and Demonstrations Author Chicha Bagu Hatimi Binti Mudin Politeknik Kota Kinabalu Kementerian Pendidikan Tinggi Malaysia 2020
Politeknik Kota Kinabalu Kementerian Pendidikan Tinggi Malaysia All right reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopy, recording, or any information storage and retrieval system without permission in writing from Jabatan Kejuruteraan Mekanikal Kota Kinabalu. Printed by: MSR Enterprise B2,8.0, Kingfisher Plaza, Jalan Kingfisher, Likas, 88450 Kota Kinabalu, Sabah,
i PREFACE FLUID MECHANICS: Laboratory Experiments and Demonstrations has been written as a manual handbook for the student in conducting laboratory experiments related to the basics of Fluid Mechanics. It has met the needs of the Fluid Mechanics syllabus prescribed for the Diploma and Diploma Mechanical Engineering (Manufacturing), especially at Polytechnic Malaysia. This manual includes practical experiments, DIY experiments, and virtual lab experiments. The objective of this book is to provide the step-by-step standard operating procedure (SOP) of various experiments which include objective, theory, experimental setup, procedure, observations, and calculation to be plotted. An observation sheet is included in each experiment to record data obtained during the experiment.
ii ACKNOWLEDGEMENT I want to take this opportunity to express my gratitude to my excellent team for their wholehearted support in producing this book. I also gratefully acknowledge the valuable suggestions of the following individual: Abdul Razak Mohd Daim, Angela Anak Merum, Aliudin Aziz, Shamsun Zakaria, and Sahrizan Mohd Sahari. I welcome any feedback and suggestion of all readers, which I would gladly consider in future amendments or revisions. Chicha Bagu Sabah, 2020
iii ABSTRACT Fluid mechanics is one of the most challenging courses for a mechanical engineering student. Normally the fluid mechanics lab facilitates student’s learning in a hands-on environment. The primary objective of this handbook is to provide a lab manual for the fluid mechanic's laboratory. The manual is divided into four chapters to cover the main topic of Fluid Mechanics at the polytechnic level. Chapter one begins with a practical laboratory experiment. In this chapter, the experiment is conducted at Fluid Mechanics’ Laboratory. Chapter two is a guideline to conduct the DIY experiment at home. The equipment used is a recycled material that is available at home. Chapter three revolves around the virtual laboratory. The student does their experiment by using online simulation. Chapter four is devoted to a deep understanding of how to write a good conclusion and reference in a laboratory report.
iv TABLE OF CONTENTS TITLE PAGE PREFACE.................................................................................................................................................. i ACKNOWLEDGEMENT ............................................................................................................................ii ABSTRACT...............................................................................................................................................iii TOPIC 1 PRACTICAL EXPERIMENT 1.1 Physical properties of fluid........................................................................................................... 1 1.2 Viscocity of Fluids ........................................................................................................................ 5 1.3 Venturi Meter ............................................................................................................................... 9 1.4 Pipe Friction .............................................................................................................................. 13 TOPIC 2 DIY EXPERIMENT 2.1 Pressure and depth ................................................................................................................... 17 2.2 Viscosity of fluid ......................................................................................................................... 21 2.3 Flow rate.................................................................................................................................... 25 2.4 Pascal Law ................................................................................................................................ 29 TOPIC 3 VIRTUAL LAB EXPERIMENT 3.1 Manometer................................................................................................................................. 32 3.2 Motion of an object in a viscous fluid ......................................................................................... 38 3.3 Venturi Meter ............................................................................................................................. 43 3.4 Pipe Friction............................................................................................................................... 54 TOPIC 4 WRITTING TECHNIQUES 4.1 Conclusion.................................................................................................................................. 65 4.2 References format....................................................................................................................... 67 REFERENCES ..................................................................................................................................................... 70
1 PRACTICAL EXPERIMENT Experiment: Physical Properties Of Fluid Objective: To determine mass density, specific weight, specific gravity and specific volume of substance.
2 1.0 OBJECTIVES : To determine mass density, specific weight, specific gravity, and specific volume of a substance. 2.0 EQUIPMENT : Weight scale & Beaker 3.0 MATERIALS & CONSUMABLES : Water, Cooking oil & Soluble oil 4.0 SAFETY AND HEALTH : It is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy. i. Always know the hazards associated with the equipment/materials that are being utilized in the workshop. ii. Report damaged electrical equipment to the supervisor. Do not use damaged electrical equipment. iii. Report to your lecturer any accident, injury, or uncontrolled release of potentially hazardous materials. iv. Follow all written and verbal instructions. Ask for assistance if you need guidance or help. v. Do not leave active experiments unattended. Never leave anything that is being heated or is visibly reacting unattended. 5.0 INTRODUCTION Fluid properties are intimately related to fluid behavior. Obvious, that different fluids can have grossly different characteristics. For example, gases are light and compressible, whereas liquids are heavy and relatively incompressible. To quantify the fluid behavior differences certain fluid properties are used. The fluid properties are mass density, specific weight, specific gravity, specific volume, and viscosity. i. Mass density, ρ (SI units, kg/m3 ) = () ( PHYSICAL PROPERTIES OF FLUID
3 ii. Specific weight, (SI units, N/m3 ) = (ℎ) () = = iii. Specific gravity or relative density, s = = iv. Specific volume, (SI units, m 3 /kg). = () () = 1 ( ) 6.0 PROCEDURES i. Weigh the beaker with weighing scales ii. Fill 0.5 litre of water into the beaker. iii. Weigh the beaker and the water with weighing scales. iv. Repeat step 2 until 3 with the other fluids. 7.0 RESULT Beaker mass = ……….. g Table 1: Fluid Mass Fluids Volume (liter) Fluid Mass (g) Fluid mass = Beaker with fluid - Beaker Water 0.5 Soluble Oil 0.5 Cooking Oil 0.5
4 8.0 DISCUSSION i. Find mass density, specific weight, specific gravity, specific volume for the three fluids. (Show your calculation)
5 PRACTICAL EXPERIMENT Experiment: Viscosity of Fluids Objective: To determine the viscosity of the fluids.
6 1.0 OBJECTIVES : To determine the viscosity of the fluids. 2.0 EQUIPMENT : Beads, Stopwatch, Scale and Beaker 3.0 MATERIALS & CONSUMABLES : Water and Cooking oil 4.0 SAFETY AND HEALTH : It is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy. i. Always know the hazards associated with the equipment/materials that are being utilized in the workshop. ii. Report damaged electrical equipment to the supervisor. Do not use damaged electrical equipment. iii. Report to your lecturer any accident, injury, or uncontrolled release of potentially hazardous materials. iv. Follow all written and verbal instructions. Ask for assistance if you need guidance or help. v. Do not leave active experiments unattended. Never leave anything that is being heated or is visibly reacting unattended. 5.0 INTRODUCTION Viscosity is a measurement of a fluid’s resistance to change or deformation, or more simply put, how thick it is. Changes and deformations are caused by stress, which is a force. Viscosity is a result of friction between molecules in a fluid that are moving at different speeds. The unit of viscosity is Pascal-seconds (Pa.s) or centipoise (cP). 1 Pascal-second is equal to 1 kilogram / (meter*second). To calculate the viscosity : = ( ) (ℎℎ ) () VISCOSITY OF FLUIDS
7 = ℎ. Where m = mass of substance (kg) μ = dynamic viscosity of fluid (N s/m2 ) h = height of liquid (m) t = time taken (s) 6.0 PROCEDURES 1. Fill the beaker with one of the sample liquids. Leave a couple of centimeters at the top so it does not overflow. Be sure to fill each beaker up to the same height each time. 2. Hold the beads at the opening of the beaker in one hand and the stopwatch in the other hand. 3. Simultaneously drop the beads and start the stopwatch. 4. Stop the timer when the beads touch the bottom of the cylinder. 5. Repeat the experiment 2 more times for each liquid so there is enough data to take an average. 6. Repeat the experiment testing other liquids. 7.0 RESULT Mass of beads (m):………………… (kg) Height of liquid (h) :........................ (m) Table 1: Velocity of Fluids Fluids Time (s) Average Velocity (m/s) 1 st 2 nd 3 rd Average Water Cooking Oil Figure 1 : Cylinder beaker
8 8.0 DISCUSSION i. Find the viscosity of the water and cooking oil. (Write your calculation)
9 PRACTICAL EXPERIMENT Experiment: Venturi Meter Objective: To determine Actual Flow Rate (Qactual), Theory Flow Rate (Q1) and Coefficient Discharge (Cd) for different pressure.
10 1.0 OBJECTIVES : To determine Actual Flow Rate (Qactual), Theory Flow Rate (Q1), and Coefficient Discharge (Cd) 2.0 EQUIPMENT : Venturi Meter, Hydraulic bench, and Stop Watch 3.0 MATERIALS & CONSUMABLES : Water 4.0 SAFETY AND HEALTH : It is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy. i. Always know the hazards associated with the equipment/materials that are being utilized in the workshop. ii. Report damaged electrical equipment to the supervisor. Do not use damaged electrical equipment. iii. Report to your lecturer any accident, injury, or uncontrolled release of potentially hazardous materials. iv. Follow all written and verbal instructions. Ask for assistance if you need guidance or help. v. Do not leave active experiments unattended. Never leave anything that is being heated or is visibly reacting unattended. VENTURI METER
11 5.0 INTRODUCTION Flow measurement is the quantification of bulk fluid movement. It can be measured in a variety of ways. Venturi and Orifice meters are the most commonly used flow-sensing elements in industries. Figure 1 : Venturi Meter Apparatus The venturi tube has a converging conical inlet, a cylindrical throat, and a diverging recovery cone. It has no projections into the fluid, no sharp corners, and no sudden changes in contour. 6.0 PROCEDURES 1. Connect the power cord to the power source and switch on the pump. 2. Carefully calibrate the water level inside venturi meter tubes until it reaches equal heights. 3. Press relief valve to release any trapped air bubbles inside venturi tubes. 4. Open inlet and outlet water valve to allow the current flow thru the venturi meter and set the water pressure at 0.3 bar. 5. Record the value of h1 and h3. 6. Use a stopwatch to determine the time required (in seconds) to accumulate 10 liters of water. 7. Repeat step 4 until 6 with 0.5 bar and 0.7 bar without interrupting previous settings. 8. Switch off the pump and release all accumulated water into the reservoir tank.
12 7.0 RESULT Table 1: Coefficient Discharge for different pressure Pressure gauge (bar) Time (sec) Volume (m3 ) Flow Rate (Q) (m3 /s) Venturi meter Level (m) Q1 (m3 /s) h1 h3 ∆ℎ Cd (h1-h3) 0.3 0.01 0.5 0.01 0.7 0.01 Volume 0.01 m3 = 10 liter Given Øh1 = 25 mm, 1 =4.909 x 10-4 m2 ; Øh3 = 12 mm, 3 =1.13 x 10-4 m2 1 = 1√ 2 (∆ℎ) ( 1 3 ) 2 −1 ; = 1 8.0 DISCUSSION Compare Cd values obtained from the experiment.
13 PRACTICAL EXPERIMENT Experiment: Pipe Friction Objective: To determine Flow Rate (Q1), Velocity (v) and head loss due to friction(Hf) for different pipes diameter.
14 1.0 OBJECTIVES : To determine Flow Rate (Q1), Velocity (v), and head loss due to friction(Hf) for different pipes diameter. 2.0 EQUIPMENT : LS-18001 Pipe friction apparatus, Stopwatch, and Hydraulic bench 3.0 MATERIALS & CONSUMABLES : Water 4.0 SAFETY AND HEALTH : It is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy. i. Always know the hazards associated with the equipment/materials that are being utilized in the workshop. ii. Report damaged electrical equipment to the supervisor. Do not use damaged electrical equipment. iii. Report to your lecturer any accident, injury, or uncontrolled release of potentially hazardous materials. iv. Follow all written and verbal instructions. Ask for assistance if you need guidance or help. v. Do not leave active experiments unattended. Never leave anything that is being heated or is visibly reacting unattended. 5.0 INTRODUCTION As water flows through a pipe line, energy is lost due to friction along pipe walls and flow separation at fittings. This energy loss is termed head loss. The head loss due to pipe friction is commonly estimated using the Darcy -Weisbach equation. Head Loss due to friction: = . PIPE FRICTION
15 Where; hf = Head Loss due to friction, given in units of length f = Darcy friction factor (. ) L = Pipe Length (0.427 m) D = Pipe Diameter v = Flow velocity (m/s) g = Gravitational acceleration Flow rate; = ( ) () Velocity; = = Where; A =Pipe inner area (m2 ) v = Flow velocity (m/s) Q = Flow rate (m3 /s) 6.0 PROCEDURES 1. Place the LS-18001 Pipe Friction Apparatus on a hydraulic bench. 2. Connect the water inlet port and water outlet port with a flexible hose. 3. Choose and connect the quick coupling to the pressure port of the pipes. 4. Switch on the water pump and slowly open the hydraulic bench supply valve to get pressure 0.5 bar.
16 5. Choose one size of pipe to test. (The other pipe which is not using, must be close their valve as well). 6. To measure the water flow rate, use a stopwatch and record the volume according to the table given. 7. Close the valve. After that, Repeat steps 4 to 8 with a different pipe. 8. Switch off the pump and open all valves. 7.0 RESULT Table 1: Determination of friction for different sizes of pipe Pipe inner diameter (mm) Time (s) Water Collected (m3 ) Flow Rate (m3 /s) Velocity (m/s) Head Loss duet to Friction 4 mm 60 120 180 240 300 8 mm 60 120 180 240 300 10 mm 60 120 180 240 300 8.0 DISCUSSION ii. Does the value of friction change over time? (Take the data on a 4 m diameter pipe for reference.) Explain your answer. iii. Does the value of friction change the pipe's inner diameter? Explain your answer.
17 DO IT YOURSELF (DIY) EXPERIMENT Experiment: Pressure and depth Objective: To demonstrate how water pressure increases with depth.
18 1.0 OBJECTIVES To demonstrate how water pressure increases with depth. 2.0 EQUIPMENT 1.5-liter plastic mineral water bottle, nail, and ruler 3.0 MATERIALS & CONSUMABLES Water 4.0 SAFETY Several general safety tips when are home experimenting. i. Conduct yourself responsibly and professionally at all times. ii. Wear clothing and shoes that cover exposed skin and protect you from potential splashes. iii. Practice good personal hygiene. iv. Properly segregate and dispose of all experiment waste. 5.0 INTRODUCTION Water pressure increases with depth because the water up above weighs down on the water below. Refers to the pressure formula which is force per unit area. It determines the effect of a force on a surface. It means the pressure in fluids causes a force normal to a surface. A force that is normal to a surface acts at right angles (90°) or perpendicular to it. Therefore, to calculate the pressure at the surface of a fluid, equation below can be used; = Where; P = Pressure (N/m2 ) F = Force (N) A = Surface Area (m2 ) PRESSURE AND DEPTH
19 Figure 1: Pressure in fluid static The greater column of water that pushes down on an object submerged, the greater pressure will be produced. Conversely, as objects are lifted, and the depth decreases, pressure is reduced. This is due to pressure and depth have a directly proportional relationship, and for a given depth the liquid exerts the same pressure in all directions. The equation below represents the pressure due to the weight of any fluid of average density ρ at any depth h below its surface. We can find the force or weight of the fluid from its mass density and gravity. = We can find the mass of the fluid from its volume and density: = The volume of fluid is related to the dimension of the container. It is = (ℎ) The area cancels and rearranging the variables yields = ℎ 6.0 PROCEDURES 1. Punch holes in the side of the 1.5-liter plastic mineral water bottle at an-inch intervals. 2. Fill the 1.5-liter plastic mineral water bottle with water. 3. Measure the distance from the 1.5-liter plastic mineral water bottle that the water squirts out of each hole. 4. Plot a graph of depth (distance of hole from the top of water level) versus distance water squirts from a bottle. 5. Keep records
20 7.0 RESULT Table 1 : Distance of water squirts Depth (m) Distance water squirts from a bottle. 1 st Trial 2 nd Trail 3 rd Trail Average 8.0 DISCUSSION Plot a graph of depth (distance of hole from the top of water level) versus distance water squirts from a bottle. Explain your graph.
21 DO IT YOURSELF (DIY) EXPERIMENT Experiment: Viscosity of fluid Objective: Finding Viscosity of Fluids.
22 1.0 OBJECTIVES Finding Viscosity of Fluids 2.0 EQUIPMENT 1.5 liter bottle Mineral water, Marble, Stopwatch, Notebook, and Pen 3.0 MATERIALS & CONSUMABLES Cooking oil, Water, Any two other liquid you want to test. 4.0 SAFETY Several general safety tips when are home experimenting. i. Conduct yourself responsibly and professionally at all times. ii. Wear clothing and shoes that cover exposed skin and protect you from potential splashes. iii. Practice good personal hygiene. iv. Properly segregate and dispose of all experiment waste. 5.0 INTRODUCTION In very general terms, the viscosity of a fluid is a measure of its resistance to deformation at a given rate. This means that viscosity is the resistance of a fluid to a change in shape or movement of neighboring portions relative to one another. Honey, for example, has a greater viscosity than water. But viscosity will change with temperature changes. The relationship between temperature and viscosity is, the viscosity of liquids decreases rapidly with an increase in temperature, and the viscosity of gases increases with an increase in temperature. When fluids are used in lubrication and transported in pipelines, viscosity is a major factor in determining the forces that must be overcome. Commonly, there are two types of viscosity are used which are dynamic viscosity μ and kinematic viscosity ν. Dynamic or absolute viscosity defines as the tangential force per unit area required to move one horizontal plane concerning another plane at a unit velocity when maintaining a unit distance apart in the fluid. The formula below shows the dynamic viscosity; VISCOSITY OF FLUID
23 μ = τ /γ where; τ = shearing stress in fluid (N/m2 ) μ = dynamic viscosity of fluid (N s/m2 ) γ = shear rate (s-1 ) Dynamic viscosity is related to kinematic viscosity by the equation μ = ρν where ρ is the density of the fluid. Kinematic viscosity is defined as the ratio of dynamic viscosity to density. Other than words kinematic is a quantity in which no force is involved. Kinematic viscosity can be obtained by dividing the absolute viscosity of a fluid with the fluid mass density as shown below; ν = μ / ρ where ν = kinematic viscosity (m2 /s) μ = absolute or dynamic viscosity (N s/m2 ) ρ = density (kg/m3 ) The relation of velocity and kinematic viscosity is approximated as inversely proportional. A decrease in viscosity, therefore, increases the velocity of a compound through porous media. Known, viscosity is the quantity that describes a fluid's resistance to flow. Therefore, it means that fluids resist the relative motion of immersed objects through them as well as to the motion of layers with differing velocities within them. Dynamic viscosity is the ratio of the shearing stress (F/A) to the velocity gradient (∆vx/∆z) in a fluid. η = ⁄ ∆⁄∆ 6.0 PROCEDURES 1. Fill the 1.5-liter bottle of mineral water with one of the sample liquids. Leave a couple of centimeters at the top so it does not overflow. Be sure to fill each cylinder up to the same height each time. 2. Hold the marble at the opening of the 1.5-liter bottle of mineral water in one hand and the stopwatch in the other hand. 3. Simultaneously drop the marble and start the stopwatch. 4. Stop the timer when the marble touches the bottom of the cylinder. 5. Record the name of the liquid you tested, the original height of the liquid, and how long it took for the marble to fall in seconds. 6. Repeat the experiment 2 more times for each liquid so there is enough data to take an average. Calculate the average time.
24 7.0 RESULT Height of the liquid: ………………… m Table 1 : Liquid velocity Liquid Time (s) Velocity 1 (m/s) st Trial 2 nd Trail 3 rd Trail Average Cooking oil Water 8.0 DISCUSSION What is the relationship between viscosity and velocity? Arrange the fluids from this experiment according to the highest to lowest viscosity.
25 DO IT YOURSELF (DIY) EXPERIMENT Experiment: Flow rate (Q) Objective: To determine the relationship between fluid flow rate and pressure.
26 1.0 OBJECTIVES To determine the relationship between fluid flow rate and pressure. 2.0 EQUIPMENT Two empty 1.5L mineral water bottles, nail, knife or box cutter or pin for cutting holes in the bottles, ruler, Duct tape, 1.5L graduated cylinder (wide mouth), Stopwatch. 3.0 MATERIALS & CONSUMABLES Water 4.0 SAFETY Several general safety tips when are home experimenting. i. Conduct yourself responsibly and professionally at all times. ii. Wear clothing and shoes that cover exposed skin and protect you from potential splashes. iii. Practice good personal hygiene. iv. Properly segregate and dispose of all experiment waste. A knife or box cutter can be a dangerous work tool because of the sharp blade and the repetition of use. Therefore, several safety tips must be following. i. Wear a glove to protects from any nicks which might occur while making cuts with the cutter. ii. Always point the blade of the cutter away from your body and make sure no one around in the path of the blade while making cuts with the cutter or knife. iii. Do not use cutters or knife which are cracked, broken or loose. 5.0 INTRODUCTION The flow rate (Q) of a fluid is defined to be the volume of fluid that is passing through a given cross-sectional area per unit of time. Sometimes it calls volume flow rate or discharge. In S.I. units (International System of Units), the flow rate has units of meters cubed per second, m3 /s. Since volume flow rate measures the amount of volume that passes through an area per time, the equation for the volume flow rate is: FLOW RATE
27 Flow rate ( 3 ) = Volume (3 ) time (s) Q = There another formula for volume flow rate which is Q =Av that is often more useful than the original definition of volume flow rate. A is the cross-sectional area of a section of the pipe, and v is the velocity of the fluid in that section. Flow rate ( 3 ) = Area(m2 ). Velocity( m s ) = . Pressure is the force applied) perpendicular to the surface of an object per unit area over which that force is distributed. The basic formula for pressure is force per unit area. Unit of pressure is Pascals (Pa) or N/m2 or kg·m−1 ·s−2 . Pressure ( N m2 ) = Force (N) Area (m2) = The pressure exerted by a static fluid depends only upon the depth of the fluid, the density of the fluid, and the acceleration of gravity. The fluid pressure at a given depth does not depend upon the total mass or total volume of the liquid. Therefore, the pressure in a static fluid arises from the weight of the fluid and is given by the expression; = ℎ Where; P = Pressure (N/m2 ) ρ = fluid density (kg/m3 ) g = acceleration of gravity ( 9.81 m/s2 ) h = depth of fluid (m)
28 6.0 PROCEDURES 1. Use a nail to make a small hole on a 1.5L mineral water bottle where water will flow out from it. 2. Mark 5cm, 7cm, and 10 cm from the holes that have been made. 3. To fill each bottle, place a piece of duct tape securely over the hole. 4. Place a bottle filled with water on the edge of a table. 5. The second 1.5L mineral water bottle on the ground will catch the flowing water so you may have to reposition the bottle for each trial. 6. Start the flow of water by having your assistant remove the tape. As soon as the first drop hits the bottom of the second 1.5L mineral water bottle starts your timer. 7. When the water level reaches 15cm from the bottom stop the timer. Record the time. 8. Measure the volume of water using the graduated cylinder ( If there is no graduated cylinder, calculate the volume using the appropriate formula). 9. Repeat for each height. 7.0 RESULT Water Mass density (m):………………………..kg/m3 Table 1 : Time for water collected Height (h) 5cm 7cm 10 cm Volume (V) Trial 1 st 2 nd 3 rd Average 1 st 2 nd 3 rd Average 1 st 2 nd 3 rd Average Time water collected (t) 8.0 DISCUSSION i. Explain the relationship between flow rate and height obtained from the experiment. ii. Explain the relationship between height and pressure obtained from the experiment.
29 DO IT YOURSELF (DIY) EXPERIMENT Experiment: Pascal Law Objective: To demonstrate how external forces applied to an enclosed system are transferred equally in all directions.
30 1.0 OBJECTIVES To demonstrate how external forces applied to an enclosed system are transferred equally in all directions. 2.0 EQUIPMENT 1.5L mineral water bottle, a big syringe, 4 small syringes, tape, and drill 3.0 MATERIALS & CONSUMABLES Water 4.0 SAFETY Several general safety tips when are home experimenting. i. Conduct yourself responsibly and professionally at all times. ii. Wear clothing and shoes that cover exposed skin and protect you from potential splashes. iii. Practice good personal hygiene. iv. Properly segregate and dispose of all experiment waste. The drilling machines are quite dangerous. Make sure to following safety tips, so it can be assured there won’t be an accident. Therefore; i. Checks the pre-operational first. ii. Make sure the workspace does not have any slippery hazards on the floor. iii. Ensure the chuck guard is always in position. iv. Ensure the drill speed of the cutter is well spindled to suit it well. 5.0 INTRODUCTION Pascal's law or the principle of transmission of fluid-pressure is a principle in fluid mechanics given by Blaise Pascal that states that a pressure change at any point in a confined incompressible fluid is uniformly transmitted equally through the fluid in all directions. In an enclosed fluid, since atoms of the fluid are free to move about, they transmit pressure to all parts of the fluid and the walls of the container. The pressure is transmitted undiminished for any changes PASCAL LAW
31 Pascal principles are often used on hydraulic and pneumatic systems to calculate pressure and force. This is due to hydraulic systems use an incompressible fluid, such as oil or water, to transmit forces from one location to another within the fluid. Most aircraft use hydraulics in the braking systems and landing gear. Besides that, pneumatic systems use compressible fluid, such as air, in their operation. Some aircraft utilize pneumatic systems for their brakes, landing gear, and movement of flaps. Since the pressure is equal to the force divided by the area on which it acts, then it follows that; = . 6.0 PROCEDURES 1. Use a drill to make a hole in the bottle cap and four holes around the bottle. 2. Label the small syringes A, B, C & D. 3. Place all small syringe nozzle around the bottle. 4. Fill the bottle with water. Make sure it is completely filled. 5. Fill the large syringe with water and place the nozzle on the cap of the bottle. 6. Slide the piston on a large syringe in 0.5mL. 7. Record the volume of syringes A, B, C & D. 8. Repeat 3 times. 9. Repeat steps 6 to 8t for 1mL. 7.0 RESULT Table 1 : Volume of water displacement Volume Large syringe 0.5mL 1mL Trials 1st 2nd 3rd Average Volume 1 st 2 nd 3 rd Average Volume Volume Syringe A Volume Syringe B Volume Syringe C Volume Syringe D According to Pascal’s principle, in a hydraulic system, a pressure exerted on a piston produces an equal increase in pressure on another piston in the system. If the second piston has an area 15 times that of the first, the force on the second piston is 15 times greater, though the pressure is the same as that on the first piston. This effect is exemplified by the hydraulic press, based on Pascal’s principle, which is used in such applications as hydraulic brakes.
32 8.0 DISCUSSION i. Draw a hydraulic braking system diagram. The diagram must have Master Cylinder, Brake Pedal, Clipper, Disc Brake, piston and Drum Brake. ii. Explain the working Mechanism of Hydraulic Brake. Relate how Pascal Law theory is applied to brake systems.
33 VIRTUAL LAB EXPERIMENT Experiment: Manometer Objective: To determine the relationship between mass density and pressure.
34 1.0 OBJECTIVES To determine the relationship between mass density and pressure. 2.0 EQUIPMENT Manometer 3.0 MATERIALS & CONSUMABLES i. Ethanol (grain alcohol) = 810 3 ⁄ ii. Benzene = 900 3 ⁄ iii. Seawater = 1030 3 ⁄ iv. Gasoline = 745 3 ⁄ 4.0 INTRODUCTION A manometer is a device used to measure pressure at single or multiple points in single or multiple pipelines, by balancing the fluid column by the same or another column of fluid. Manometers can be categorized into two types, namely simple manometer, and differential manometer. Simple manometric devices measure pressure at a single point in a fluid, whereas differential manometric devices measure pressure at two or more points, in a single or multiple flow lines. Figure 1: U-tube manometer MANOMETER
35 The pressure of a fluid is the normal force exerted by a fluid on a unit area. The pressure designated will be either an absolute pressure or a gauge pressure. Absolute pressure is measured relative to a perfect vacuum (absolute zero pressure), whereas gauge pressure is measured relative to the local atmospheric pressure. Absolute pressures are positive, but gauge pressure can be either positive (above atmospheric pressure) or negative (below atmospheric pressure). Different types of Pressure: Absolute pressure The clearest reference pressure is pressure zero, which exists in the air-free space of the universe. A pressure that is related to this reference pressure is known as absolute pressure. For the required differentiation from other types of pressure, it is denoted with the index “abs”, which is derived from the Latin “absolutus”, meaning detached, independent. Atmospheric pressure The probably most important pressure for life on earth is the atmospheric pressure, pamb (amb = ambiens = ambient). It is created by the weight of the atmosphere which surrounds the earth up to a height of approx. 500 km. Up to this altitude, at which the absolute pressure pabs = zero, its magnitude decreases continuously. Furthermore, the atmospheric pressure is subject to weather-dependent fluctuations, as is only too well known from the daily weather report. At sea level, pamb averages 1,013.25 hectopascal (hpa), corresponding to 1,013.25 millibar (mbar). With “cyclones” and “anticyclones”, this pressure varies by about 5 %. Differential pressure The difference between two pressures, p1 and p2, is known as the pressure differential, Δp = p1 - p2. In cases where the difference between two pressures itself represents the measured variable, one refers to the differential pressure, p1,2. . Density or Mass Density: The mass density or density of a fluid is defined as the ratio of a mass of fluid to its a volume of the fluid. Density is called a Mass per unit volume of a fluid.
36 5.0 PROCEDURES 1. Open QR Code below to to access Simulation Lab. 2. Click Simulation to start Virtual Lab 3. Click Manometer, 4. A window will appear as shown.
37 5. Enter the density of the liquid and the height difference of the liquid. 6. After entering the density and the height difference click on pressure button to calculate pressure. 7. Repeat the same procedure for other heights and material. 6.0 RESULT Table 1: Different Mass Density Liquids Mass Density () 3 ⁄ Pressure (Bar) Height 1 m Height 3 m Height 6 m Height 9 m Gasoline 745 Ethanol 810 Benzene 900 Seawater 1030
38 7.0 DISCUSSION i. Explain the relationship between pressure and height based on the experiment that has been executed. ii. Draw a graph to show a relationship between Pressure and Mass Density. (Use data from h = 9 meters)
39 VIRTUAL LAB EXPERIMENT Experiment: Motion of an Object in a Viscous Fluid Objective: To study the relation between viscosity velocity and weight object.
40 1.0 OBJECTIVE To study the relation between viscosity velocity and weight object. 2.0 EQUIPMENT Stopwatch, tall glass jar, scale, vernier caliper, glass beads 3.0 MATERIALS & CONSUMABLES : Glycerine and Castor Oil 4.0 INTRODUCTION Viscosity is defined as a liquid’s resistance to flow or the measure of a substance's resistance to the motion under an applied force. Viscosity is the measure of a material’s resistance to motion under an applied force. Stokes law is the basis of the falling-sphere viscometer, in which the fluid is stationary in a vertical glass tube. It deals with small spherical objects that are moving through a fluid at small velocities. A sphere of known size and density is allowed to descend through the liquid. Therefor. the viscosity can be determined from the velocity, mass density and volume of the ball. When the ball is moving through the fluid the force of gravity is acting down on it while the forces of buoyancy and drag are acting on it in the opposite direction. There are several formulas and equations to calculate viscosity, the most common of which is = ( − ) 6 or = 2( − ) 2 9 where = Viscosity g = acceleration due to gravity = 9.8 m/s2 , D = radius of ball bearing, = velocity of ball bearing through liquid. = volume of the ball MOTION OF AN OBJECT IN A VISCOUS FLUID
41 Velocity is a change in objects displacement over time. Its unit is meter per second (m/s).In simple words, velocity is a measure of how much time an object takes to reach a destination with direction. In other words, it is directly related to displacement and inversely relates to the time traveled. Equations to calculate velocity is; = () () Where; Displacement = Distance between point A and B Time = time taken from point A to B 5.0 PROCEDURES 1. Scan the QR code below to access the viscosity of a liquid simulation. 2. Please follow the procedure before doing the simulation to understand how this experiment is run. i. Click Simulator to start Virtual Lab ii. Select liquid iii. Set jar diameter to 10 cm iv. Refer to Table :1 to select ball diameter according to
42 v. Drag ball to jar and record the time vi. Press RESET and repeat step iv and v for different ball sizes. vii. Change fluid to Castor Oil and repeat all steps. 3. Write down the data observed in the Experimental Result Table. 6.0 RESULT Table 1 : Experimental result Fluid 6mm ball diameter 8 mm ball diameter 10 mm ball diameter Time (s) Velocity (m/s) Time (s) Velocity (m/s) Time (s) Velocity (m/s) Glycerine Castor Oil 7.0 DISCUSSION a. Use 6mm ball diameter data to find the viscosity of the two fluids that have been tested. From the analysis obtained, what is the relationship between viscosity and velocity? b. Does the size of the ball affect the time taken for the ball to fall to the bottom of the jar? Why? Distance between point A and B = …………………………… Density of Glycerine = …………………………… Density of Castor Oil =…………………………… Density of the Glass Ball =……………………………
43 VIRTUAL LAB EXPERIMENT Experiment: Venturi Meter Objective: To determine the coefficient of discharge of given venturimeter.