Pressure & Pressure Differences in Fluids (Edexcel GCSE Physics)

Figure 1 shows an object under the surface of the sea.

(i) Which arrow shows where the pressure on the object is greatest?

Figure 1

[1]

(ii) Figure 2 shows two blocks of stone resting on the bottom of the sea.

Both blocks have the same height.

Area Y is 4 times bigger than area X.

Figure 2

What is the pressure due to the water on the top surface of block Y?

☐ A one quarter of the pressure on X

☐ B the same as the pressure on X

☐ C twice the pressure on X

☐ D four times the pressure on X

[1]

A diver is swimming underwater in a lake. The diver wears the meter shown in Figure 3.

Figure 3

(i) The meter shows the depth of the diver below the surface of the water.

State the depth shown on the meter in Figure 3.

State the unit.

depth = ............................... unit = ..........................[2]

(ii) State how the pressure of the water on the diver changes as the diver swims down from the surface of the lake.

[1]

(iii) State why the total pressure on the diver is greater than just the pressure due to the water above the diver.

[1]

An aeroplane takes off from the ground.

State two factors that affect the pressure of the atmosphere on the aeroplane as the aeroplane goes higher in the atmosphere.

Figure 3 shows a diver swimming in a lake.

Figure 3

The pressure on the diver is due to both the water above him and the Earth’s atmosphere.

The pressure of air on the surface of the water is one atmosphere. 10m of water is equivalent to one atmosphere.

How many atmospheres of pressure will be on the diver at a depth 20m?

A balloon is filled with helium when it is on the ground.

The balloon is released and it rises through the atmosphere.

Explain what happens to the size of the balloon as it rises through the atmosphere.

Figure 4 shows a container of length 6.0 m and width 2.0 m resting on a floor.           

The weight of the container is 15 000 N.

Figure 4

Calculate the pressure that the container exerts on the floor.

Use the equation

pressure of the container on the floor = ................................ Pa

Figure 1 shows a fish tank holding water.

Figure 1

The pressure in the bottom of the tank is 37 kPa.

Calculate the weight of water in the tank.

On Figure 1, sketch the direction of the forces from the water on the inside of the tank.

Higher Tier Only

A fish in the tank in Figure 1 swims from a depth of 3.7 cm to a deeper depth. The increase in pressure on the fish is 3.1 kPa. 

The density of the water is 1000 kg/m³ and the gravitational field strength is 10 N/kg.

Calculate the depth the fish swims to.

Water is removed from the tank.

Explain how the pressure at the bottom of the tank changes when water is removed from the tank.

Figure 8 shows some water in a tank.

Figure 8

(i) The bottom of the tank has an area of 0.80 m².

The force on the bottom of the tank, due to the water, is 2400 N.

Calculate the pressure, due to the water, on the bottom of the tank.

pressure = .............................................................. Pa[3]

(ii) More water is added to the tank.

Explain how the pressure on the bottom of the tank changes when more water is added to the tank.

[2]

(iii) Figure 9 shows an object on the bottom of the tank of water.

Figure 9

Draw an arrow on Figure 9 to show the direction of the force exerted by the water on the surface of the object at point X.

[1]

Figure 10 is a graph showing how the atmospheric pressure changes with the height above sea level on the Earth’s surface.

Figure 10

(i) An aeroplane descends from 6000 m to 2000 m.

Use the graph to find the change in atmospheric pressure as the aeroplane descends.

change in pressure =................................................. kPa[2]

(ii) Suggest one reason why the atmospheric pressure is greater at 2000 m than at 6000m.

[1]

Figure 11 shows two drawings of the same person on a bed.

Figure 11

Explain why the person exerts a different pressure on the bed when standing up than when lying down.

Higher Tier Only

Figure 1 shows a water barrel for storing rainwater. The barrel has a tap.  rainwater. 

Figure 1

A student investigates the water depth in the barrel.

She measures the depth and then opens the tap.

To investigate the water depth in the barrel, a researcher measures the initial depth and then opens the tap. They measure the depth every minute.

Figure 2 shows their results. 

Figure 2

State two measuring instruments the student could use in her investigation.

On the axes below, plot a graph to show how the depth changes with time. Include a curve of best fit.

Describe the relationship between depth and time as shown by the graph.

The researcher notices that the water flows out less quickly as time passes.

Suggest a reason for the decrease in flow rate of the water.

Higher Tier Only 

Figure 25 shows four identical metal cans, each filled with water to the same level.

Each can has three tubes.

Water comes out of each tube.

Which of these shows the correct pattern of water coming out of the tubes?

Figure 25

Higher Tier Only

Figure 26 shows a glass U-tube containing water of density 1000 kg/m³.

The water levels are the same on both sides of the U-tube.

Both ends of the U-tube are open to the atmosphere.

Atmospheric pressure is 101 000 N/m²

Figure 26

Figure 27 shows the U-tube with one side connected to a gas supply.

The difference in the levels of water, h, is 0.200 m.

Figure 27

(i) Calculate the gas supply pressure.

Use an equation selected from the list of equations at the end of the paper.

pressure of gas supply = ...................................... N/m²[3]

(ii) The measurement is repeated using a U-tube of larger cross-sectional area.

Explain why the value of h does not change.

[2]

Higher Tier Only 

Figure 28 shows a cross-section of a boat floating in water and the same boat with a load inside.

Figure 28

The boat floats lower in the water when there is a load inside the boat.

Explain why the boat floats in water and why the boat floats lower in the water when there is a load inside the boat.

You may add to the diagram to help with your answer.

Figure 17 shows a crane lifting a concrete block from the bottom of a deep pool of water.

The top of the block is a distance, h, below the surface of the water.

Figure 17

The force on the top of the block due to the water above it is 41 000 N.

The pressure due to the water on the top surface of the block is 66 000Pa.

(i) Calculate the area of the top surface of the block.

area of the top surface of the block = ............................. m²[2]

(ii) The density of water is 1000 kg/m³.                         

Calculate the distance, h, between the top of the block and the surface of the water.

Gravitational field strength, g, is 10 N/kg.

Use an equation selected from the list of equations at the end of this paper.

h = ............................................... m[2]

(iii) Explain why there is an upthrust produced by the water on the block.

[2]

(iv) The crane raises the block until it is high enough out of the water to be loaded on to a lorry.

The block moves upwards at a constant speed even though the lifting force in the cable changes.

Figure 18 shows the graph of how the lifting force changes while the block is being raised.

Figure 18

Explain why the lifting force changes as shown on the graph in Figure 18.

Include calculation(s) in your answer.

[6]

The graph in Figure 14 shows the variation in atmospheric pressure with the height above sea level.

Figure 14  

(i) Use the graph to estimate the atmospheric pressure at 3000 m above sea level.

atmospheric pressure = .......................................... kPa[1]

(ii) Use the graph to estimate the atmospheric pressure at 6000 m above sea level.

atmospheric pressure = ............................................... kPa[1]

(iii) Suggest a reason why the atmospheric pressure decreases with height above sea level.

[1]

Figure 15 shows different water levels in two similar water containers with taps.

Figure 15

Explain why the water runs out of the tap of container A faster than out of the tap of container B.

10 m of sea water exerts the same pressure as the atmosphere.

A submarine is at a depth of 50 m below the surface of the sea.

Calculate how many times greater the pressure is on the submarine than atmospheric pressure.

pressure = ........................... times greater

Figure 16 illustrates an effect that can be explained using the ideas of pressure, force and area.

Figure 16

Explain why the tip of the drawing pin goes into the wood but the head of the drawing pin does not go into the thumb.