3.1 Understanding pressure A student is able to: Define pressure and state that Describe applications of pressure Solve problems involving pressure 1. What is meant by pressure? . Force over a unit area 2. Choose ( √ ) the examples that apply the concept of pressure? (√ ) Toothpaste (√ ) Nail (√ ) Larger and wider seat belt (√ ) Knife ( ) Ship ( ) Aerofoil 3. Diagram 3 A girl is going to take a walk at a field. There are two types of shoes as shown in Diagram 3. Which type of shoes should she wear? Diagram 3b 1
3.1 Understanding pressure A student is able to: F
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Define pressure and state that P = A Describe applications of pressure Solve problems involving pressure
1. What is meant by pressure? . Force over a unit area 2. Choose ( √ ) the examples that apply the concept of pressure? (√ ) Toothpaste (√ ) Larger and wider seat belt ( 3. ) Ship (√ ) Nail (√ ) Knife ( ) Aerofoil
Diagram 3 A girl is going to take a walk at a field. There are two types of shoes as shown in Diagram 3. Which type of
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3.1 Understanding pressure
A student is able to:
Define pressure and state that
Describe applications of pressure Solve problems involving pressure
1. What is meant by pressure?
. Force over a unit area
2. Choose ( √ ) the examples that apply the concept of pressure?
(√ ) Toothpaste (√ ) Nail
(√ ) Larger and wider seat belt (√ ) Knife
( ) Ship ( ) Aerofoil
3.
Diagram 3
A girl is going to take a walk at a field. There are two types of shoes as shown in
Diagram 3.
Which type of shoes should she wear?
Diagram 3b
1
4. Diagram 4 shows a cuboid of 2 kg on a table.
Calculate the pressure exerted on the table by the cuboid. Tick (√ ) the correct answer.
Diagram 4
( ) 0.8 N m-2
( ) 50 N m-2
( ) 200 N m-2
(√) 500 N m-2
5. Diagram 5 shows different situations of a cuboid of 5 kg on a table.
Circle the diagram in which the cuboid exerts the least pressure on the table.
Diagram 5
2
0.4 m
0.1 m
3.2 Understanding pressure in liquids
A student is able to:
relate depth to pressure in a liquid
relate density to pressure in a liquid
explain pressure in a liquid and state that P = h ρ g
describe applications of pressure in liquids.
1. What is the relationship between depth of liquid and pressure?
The more the depth of liquid the more the pressure at the lowest point of liquid.
2. What is the relationship between density of liquid and pressure?
The higher the density of liquid the higher the pressure at the lowest point of liquid.
3.
Diagram 4Diagram 4 shows a container of oil.
Point ( X , Y ) has the highest pressure?
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4. The relationship of pressure in liquid is, P =hρg
What is represented by h, ρ and g respectively?
h = depth of liquid
ρ = density of liquid
g = gravitational acceleration
5. State one application of pressure in liquid.
Water tank is placed at a higher altitude/ any acceptable answer.
6.
Diagram 6
Diagram 6 shows a glass full of alcohol.
What is the pressure at P? Tick a (√ )correct answer.[ Density of alcohol = 800 kg m-3 ](√ ) 1600 Pa( ) 16 000 Pa( ) 160 000 Pa( ) 1 600 000 Pa
Solution: P = h ρ g
= 20/100 x 800 x 10
= 1600 Pa
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3.3 Understanding gas pressure and atmospheric pressure
A student is able to:
explain gas pressure
explain atmospheric pressure
describe applications of atmospheric pressure
1. A student wrote several statements to explain the gas pressure.
However they were in the wrong order.
Rearrange the statements in sequence to explain the gas pressure.
Sequence Statements
3 Collisions of gas particles in the container occur very frequently.
1 The gas is made up of gas particles.
4 The collisions of gas particles on the wall of container give rise to gas
pressure
2 The gas particles move randomly with high speed.
2. Gas pressure = ( 24 – 10 ) + 76
= 86 cm Hg
3. Level of mercury meniscus of mercury column Y increases.
4. The ( weight , mass ) of air on the earth’s surface caused the atmospheric pressure.
5. A mountain terrain has a ( higher , lower ) atmospheric pressure than
at the sea-side because the air at the mountain terrain is ( thicker , thinner ).
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6. It is found that a Fortin barometer reads 74 cm Hg at a highland whereas the reading is 76 cm Hg at the sea side. Based on the statement, tick (√ ) the correct choice. i. a correct inference ii. a correct hypothesis
i (√ ) The atmospheric pressure is influenced by the altitude
( ) The atmospheric pressure is influenced by the type of barometer
ii. (√ ) The higher the altitude from sea level the lower the atmospheric pressure
( ) The lower the altitude from sea level the lower the atmospheric pressure
7. Fortin barometer X reads 74 cmHg whereas Fortin barometer Y reads 76 cmHg.
Which of the following statements correctly explain the difference of atmospheric pressure in the terms of altitude?
Mark (√ ) at the correct statements.
The Fortin barometer X measured the atmospheric pressure at lower altitude.
√ The Fortin barometer X measured the atmospheric pressure at higher altitude.
√ The Fortin barometer Y measured the atmospheric pressure at lower altitude.
The Fortin barometer Y measured the atmospheric pressure at higher altitude.
8. List two apparatus that apply the atmospheric pressure.
I . Siphon /sucking drinking water by using straw
ii. Syringe / any acceptable answer
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3.4 : Appling Pascal’s Principle
A student is able to:
state Pascal’s principle.
Explain hydraulic system
Describe applications of Pascal’s principle.
Solve problems involving Pascal’s principle.
Answer
1. Pascal’s Principle states an external pressure applied to an enclosed fluid is
transmitted equal to every point.
2. Some examples of the application of the Pascal’s Principle are
hydraulic lift, jack, brake system.
3. Diagram 3 shows an application of Pascal’s Principle.
Diagram 3
State the relationship between F1, F2, A1 and A2.
F1/A1 = F2/A2
4. The diagram show one application where pressure is transmitted
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equally through an oil. Name the system: hydraulic brake.
Diagram 4
5. Diagram 5 shows toothpaste being squeezed out from the tube. The principle that
explains the situation below is Pascal Principle .
Diagram 5
6. Diagram 6 shows a hydraulic jack.
Diagram 6
7. Diagram 7 shows a simple hydraulic system. A1 and A2 are cross section
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area of the piston. A1 = 5 cm2 and A2 = 10 cm2.
Diagram 7
(a) What is the minimum force F1 which can lift a load of 100 kg ?
500 N/ 50kg.
(b)What will happen to the hydraulic jack if the force F1 is less than the value
found in 7(a)?
Does not move/ piston A2 move downward and piston A1 move upward
(c) Give one reason for your answer
The force F1 500 N. Thus, the pressure produced is less than the
minimum pressure required to support/lift the load.
3.5 Applying Archimedes’ Principle
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A student is able to:
Explain buoyant force
Relate buoyant force to the weight of the liquid displaced
State Archimedes’ principle.
Describe applications of Archimedes principle
Solve problems involving Archimedes principle
Instruction : Answer all question in this section.
1. Buoyant force is the upward force exerted on an object immersed in a fluid.
2. Archimedes' Principle states that if an object is partly or wholly submerged in
a fluid, it experiences a buoyant force equal to the weight of the fluid
displaced. ( Weight in air – Weight in fluid = Upthrust)
3. The examples of application of Archimedes's Principle are: