Pressure in fluids

Figure 9 shows a jar containing some liquid.

The pressure in the liquid causes a force on the inside walls of the jar.

What direction is the force acting on the inside walls of the jar?

The liquid in the jar has a weight of 1.50 N.

The liquid exerts a pressure of 774 N/m² on the base of the jar.

Calculate the area of the base of the jar.

Use the Physics Equations Sheet.

Give your answer to 3 significant figures.

Figure 10 shows a jar containing oil, vinegar and a piece of garlic.

The garlic in Figure 10 is floating at the boundary between the two liquids.

Explain why there is an upthrust on the garlic.

A swimming pool is being filled with water.

Calculate the weight of the water in the swimming pool when the mass of the water is 25 000 kg.

gravitational field strength = 9.8 N/kg

Use the equation:

weight = mass × gravitational field strength

When the swimming pool is full, the weight of the water is 1 960 000 N.

The bottom of the swimming pool has an area of 49 m².

Calculate the pressure at the bottom of the swimming pool when it is full.

Use the equation:

Choose the unit from the box.

There is a force acting on the side of the swimming pool because of the water pressure.

Figure 11 shows the side of the swimming pool.

Which arrow shows the direction of the force acting on the side of the swimming pool?

Tick (✓) one box.

A child is swimming in the pool. The velocity of the child is 0.70 m/s.

The child then accelerates for 5.0 s, reaching a final velocity of 1.3 m/s.

Calculate the acceleration of the child.

Use the equation:

Figure 12 shows a diving board at the side of the swimming pool.

The original length of the spring is 0.84 m.

When the child stands on the diving board, the length of the spring decreases by 0.21 m.

Calculate the percentage change in the length of the spring.

Use the Physics Equations Sheet to answer questions 07.6 and 07.7.

Write down the equation which links extension (e), force applied to a spring (F) and spring constant (k).

The force applied to the spring by the weight of the child is 336 N.

The change in length of the spring is 0.21 m.

Calculate the spring constant of the spring.

The child steps off the diving board and falls into the swimming pool.

The initial velocity of the child is 0 m/s.

acceleration due to gravity = 9.8 m/s²

Calculate the final velocity when the child has fallen a distance of 0.95 m through the air.

Give your answer to 2 significant figures.

Use the Physics Equations Sheet.

The Mariana Trench is the deepest part of the Pacific Ocean.

Figure 8 shows a submarine going to the bottom of the Mariana Trench.

The depth of the submarine increases.

Explain what happens to the pressure on the submarine.

The submarine moved from the surface of the water to the bottom of the Mariana Trench.

The change in pressure was 110 000 kPa.

mean density of sea water = 1026 kg/m³

gravitational field strength = 9.8 N/kg

Calculate the depth of the Mariana Trench.

Use the Physics Equations Sheet.

Earthquakes often occur at the Mariana Trench.

P-waves and S-waves are produced by earthquakes.

Which statement describes P-waves and S-waves?

Tick () one box.

Figure 9 shows the layers inside the Earth.

An earthquake occurs at the position shown.

Which letter shows the position where only P-waves will be detected?

Give a reason for your answer.

Tick () one box.

An S-wave has a frequency of 3.6 Hz.

The S-wave has a speed of 4.5 km/s.

Calculate the wavelength of this S-wave.

Use the Physics Equations Sheet.

A seismometer is a device that detects earthquakes.

P-waves travel at a known speed between an earthquake and a seismometer.

S-waves travel at a slower speed than P-waves.

A P-wave and an S-wave from the earthquake arrive at the seismometer at different times.

Describe the relationship between the distance from the earthquake to the seismometer and the time between the P-wave and the S-wave arriving.

Infrared waves are transverse waves.

Complete the sentence.

to the direction of energy transfer by the wave.

A student investigated how the colour of a surface affects the rate at which the surface emits infrared radiation. Figure 23 shows some of the equipment used.

The student wrote the following hypothesis: ‘The black-coloured flask will emit more infrared radiation than the silver-coloured flask during 10 minutes of cooling.’ Describe a method to test this hypothesis.

When will the flasks emit infrared radiation at the greatest rate? Give a reason for your answer. Tick (✓) one box.

Another student investigated the absorption of infrared radiation by different surface colours. The student filled four hollow metal cubes with cold water. Each cube was the same size but had a different surface colour. The cubes were then placed the same distance from an infrared heater. After 10 minutes, the student measured the temperature increase of the water inside each cube.

What was the dependent variable in this investigation?

Table 2 shows the results.

Give two conclusions that can be made from the results in Table 2.

Figure 24 shows one of the cubes. The cube is filled with water. The weight of the water exerts a pressure on the bottom of the cube.

Use the Physics Equations Sheet to answer questions 09.6 and 09.7.

Which equation correctly links area, force and pressure? Tick (✓) one box.

The water pressure at the bottom of the cube is 1500 Pa. Calculate the force of the water on the bottom of the cube.

Infrared waves are transverse waves.

Complete the sentence.

to the direction of energy transfer by the wave.

A student investigated how the colour of a surface affects the rate at which the surface emits infrared radiation. Figure 1 shows some of the equipment used.

The student wrote the following hypothesis: ‘The black-coloured flask will emit more infrared radiation than the silver-coloured flask during 10 minutes of cooling.’ Describe a method to test this hypothesis.

When will the flasks emit infrared radiation at the greatest rate? Give a reason for your answer. Tick (✓) one box.

Another student investigated the absorption of infrared radiation by different surface colours. The student filled four hollow metal cubes with cold water. Each cube was the same size but had a different surface colour. The cubes were then placed the same distance from an infrared heater. After 10 minutes, the student measured the temperature increase of the water inside each cube.

What was the dependent variable in this investigation?

Table 1 shows the results.

Give two conclusions that can be made from the results in Table 1.

Figure 2 shows one of the cubes. The cube is filled with water. The weight of the water exerts a pressure on the bottom of the cube.

Use the Physics Equations Sheet to answer questions 01.6 and 01.7.

Which equation correctly links area, force and pressure? Tick (✓) one box.

The water pressure at the bottom of the cube is 1500 Pa. Calculate the force of the water on the bottom of the cube.

The Earth is surrounded by an atmosphere.

The radius of the Earth is 6400 km.

Which of the following could be an approximate depth of the Earth’s atmosphere?

Tick (✓) one box.

What state of matter is most of the Earth’s atmosphere?

Tick (✓) one box.

Figure 12 shows how atmospheric pressure varies with height above sea level.

The highest point above sea level in England is the top of a mountain called Scafell Pike.

The height above sea level of Scafell Pike is 978 m.

Determine the atmospheric pressure at the top of Scafell Pike.

Use Figure 12.

Determine the difference between the atmospheric pressure at sea level and at the top of Scafell Pike.

Use Figure 12 and your answer from Question 06.3

A student climbs Scafell Pike.

Why does the atmospheric pressure decrease as the student climbs higher?

Tick (✓) two boxes.

Figure 13 shows a mountain lake.

The lake has a surface area of 2000 m².

Atmospheric pressure exerts a force of 188 000 000 N on the surface of the lake.

Calculate the atmospheric pressure at the surface of the lake.

Use the equation:

Diving bricks sink to the bottom of a swimming pool.

Figure 14 shows a diving brick.

Swimmers practise diving to the bottom of the swimming pool to pick up the diving brick.

Explain why the forces on the brick at the bottom of the pool cause the brick to be stationary.

When the brick from Figure 14 is at the bottom of the pool, the top surface of the brick is 2.50 m below the surface of the water.

The force acting on the top surface of the brick due to the weight of the water is 637 N.

gravitational field strength = 9.8 N/kg

Calculate the density of the water in the swimming pool.

Use the Physics Equations Sheet.

Professional divers are trained in a very deep swimming pool.

The density of the water in this pool is not the same as the density of the water in Question 08.2

The diving brick was dropped into the very deep swimming pool.

When the brick was at a depth of 2.50 m, the force due to the weight of the water on the top surface of the brick was 618 N.

Figure 15 shows the diving brick at the bottom of the very deep swimming pool.

Determine the force due to the weight of the water on the top surface of the brick in Figure 15.

Use the Physics Equations Sheet.

Give your answer to 3 significant figures.

The thinking distance and braking distance for a car vary with the speed of the car.

Explain the effect of two other factors on the braking distance of a car. Do not refer to speed in your answer.

Which equation links acceleration (a), mass (m) and resultant force (F). Tick (✓) one box.

The mean braking force on a car is 7200 N. The car has a mass of 1600 kg. Calculate the deceleration of the car.

Figure 18 shows how the thinking distance and braking distance for a car vary with the speed of the car.

Determine the stopping distance when the car is travelling at 80 km/h.

Figure 19 shows part of the braking system for a car.

Which equation links area of a surface (A), the force normal to that surface (F) and pressure (p)? Tick (✓) one box.

When the brake pedal is pressed, a force of 60 N is applied to the piston. The pressure in the brake fluid is 120 000 Pa. Calculate the surface area of the piston. Give your answer in standard form. Give the unit.

The thinking distance and braking distance for a car vary with the speed of the car.

Explain the effect of two other factors on the braking distance of a car. Do not refer to speed in your answer.

Which equation links acceleration (a), mass (m) and resultant force (F). Tick (✓) one box.

The mean braking force on a car is 7200 N. The car has a mass of 1600 kg. Calculate the deceleration of the car.

Figure 1 shows how the thinking distance and braking distance for a car vary with the speed of the car.

Determine the stopping distance when the car is travelling at 80 km/h.

Figure 2 shows part of the braking system for a car.

Which equation links area of a surface (A), the force normal to that surface (F) and pressure (p). Tick (✓) one box.

When the brake pedal is pressed, a force of 60 N is applied to the piston. The pressure in the brake fluid is 120 000 Pa. Calculate the surface area of the piston. Give your answer in standard form. Give the unit.

Figure 11 shows a container filled with water. The three holes in the side of the container are sealed with rubber stoppers.

Figure 11

The water exerts a force of 27 N on the bottom of the container. The cross-sectional area of the bottom of the container is 0.009 m². Calculate the pressure exerted by the water on the bottom of the container. Use the equation:

Choose the unit.

The container is put under running water from a tap and the three rubber stoppers removed. Figure 12 shows the path taken by the water escaping from the top and bottom holes.

Figure 12

Complete Figure 12 to show the path taken by the water escaping from the centre hole.

What can be concluded from Figure 12 about the pressure in a liquid?

Figure 13 shows a simple model of a liquid. When a force pushes down on the marbles, the marbles push the sides and bottom of the container outwards.

Figure 13

What can be concluded from this model about the pressure in a liquid?

Figure 6 shows an unusually shaped container. The container has four vertical tubes of different shape and size.

Water is poured into the container up to the level shown in tube 1.

Complete Figure 6 to show the height of the water in tubes 2, 3 and 4.

The further a swimmer dives below the surface of the sea, the greater the pressure on the swimmer. Explain why.

A person swims from a depth of 0.50 m to a depth of 1.70 m below the surface of the sea. density of the sea water = 1030 kg/m³ gravitational field strength = 9.8 N/kg Calculate the increase in pressure on the swimmer. Give the unit. Use an equation from the Physics Equation Sheet.