Work Done & Energy Transfer (AQA GCSE Physics)

Exam Questions

1 hour10 questions
1a1 mark

What are the correct units for work done?

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N square
m square
N/m square
N m square
1b1 mark

What is the correct arrangement for the equation linking work done (W), force (F), and distance moved (s)?

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W space equals space F s  square
W space equals fraction numerator space F over denominator s end fraction square
W space equals space F space minus space s square
W space equals space s over F square
1c3 marks

A person does work by lifting their shopping bag 10 cm off the ground. 

The bag has a weight of 60 N.

Determine the work done by the person.

   

Work done = .................................... N m

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2a1 mark

Which of the following expressions is correct for the relationship between work done and energy?

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Work done = energy transferred square
Work done = energy transferred × distance square
Work done = energy transferred + distance  square
2b4 marks

A father pushes his daughter on a sled across the snow on flat ground.

He pushes with a force of 400 N for a distance of 20 m.

Calculate the energy transferred.

   

   

Energy transferred = .................................... J

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3a3 marks

Which of the following statements about friction are correct?

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Friction always acts against motion  square
Energy is transferred by heating  square
Friction is not a force  square
The units for friction are watts square
Air resistance is a type of friction square
3b3 marks

A student rubs their hands together on a cold day.

The friction between the surfaces of the student's hands causes them to get warmer.

Describe the energy transfers taking place as the student rubs their hands together.

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1a1 mark

A builder pushes a heavy crate up a slope, as shown in Figure 1.

Figure 1

builder-1

State the equation that links the change in gravitational potential energy (E) to the mass of the object (m), the gravitational field strength (g) and the change in height (h).

1b2 marks

The crate has a mass of 50 kg.

Calculate the gain in gravitational potential energy of the crate.

Gravitational field strength = 9.8 N / kg.

1c4 marks

The builder pushes the crate with a force of 200 N.

Calculate the work done by the builder.

1d2 marks

Explain why your answers to questions (b) and (c) are different to each other.

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2a3 marks

A girl rides a sledge down a smooth snowy slope, as shown in Figure 2.

Figure 2

q1d-medium-5-2-aqa-gcse-physics

To begin with the sledge accelerates, but after a while it starts to travel at a constant speed.

Explain why.

2b3 marks

Whilst travelling at a constant speed of 5 m/s, the girl travels a distance of 200 m and descends a vertical height of 25 m.

The girl and sledge have a combined mass of 50 kg.

Calculate the change in the gravitational potential energy of the girl and sledge.

Gravitational field strength = 9.8 N/kg

2c3 marks

As the sledge descends the slope friction does work against the sledge.

Calculate the average frictional force acting on the sledge.

2d3 marks

Calculate the kinetic energy of the girl and the sledge.

2e3 marks

Eventually the slope levels out and the sledge slows down and comes to a halt.

Assuming that the frictional force on the sledge remains the same as that calculated in part (c), calculate the distance it will take the sledge to come to a halt.

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3a3 marks

A student carries out an experiment which involves using an electric motor to lift some masses, as shown in Figure 3.

Figure 3

electric-motor

At one point, a mass of 200 g is lifted.

Calculate the weight of this mass.

Gravitational field strength = 9.8 N/kg

Give your answer to 2 significant figures

3b3 marks

Calculate the work done by the motor when it lifts the above mass a height of 90 cm.

3c3 marks

The student estimates that the efficiency of the motor is about 20%.

Calculate the amount of total energy supplied to the motor.

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4a2 marks

A car is travelling at a steady speed of 15 m/s when the driver suddenly has to brake.

The car has a total mass of 1500 kg.

Calculate the kinetic energy of the car, just before the brakes are applied.

4b1 mark

State the work done by the brakes in stopping the car.

4c3 marks

The brakes apply a force of 12 000 N on the car.

Calculate the braking distance of the car.

Give your answer to 2 significant figures.

4d2 marks

Explain what happens to the kinetic energy of the car as it slows down and the effect that it will have on the brakes.

4e4 marks

Electric cars are fitted with regenerative braking systems.

These systems consist of generators attached to the car’s wheels.

Electric cars are also fitted with standard brakes alongside the regenerative ones.

Explain the advantages of both regenerative brakes and standard brakes.

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1a1 mark

A penny is held at the top of Blackpool tower. The penny is released and falls a distance h to the ground, reaching a speed begin mathsize 20px style v end style as it falls. 

As the penny falls, air resistance causes some of the energy stored in the penny to be transferred to the thermal store of the air.

Which of the following expressions gives the work done against air resistance?

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1 half m v squared square
m g h space plus space 1 half m v squared square
m g h space minus space 1 half m v squared  square
m g h square
1b5 marks

The penny has a mass of 2.5 g. Blackpool tower has a height of 158 m.

0.967 N m of work is done against air resistance.

Calculate the speed of the penny just before it hits the ground.

Give your answer to 2 significant figures.

   

   

Speed (2 significant figures) = .................................... m/s

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2a3 marks

Figure 1 shows a cross-section of a Tube station on the London Underground.

Figure 1

5-2-h-2a-tube-station

A group of students are learning about the station in a physics lesson before they visit it on a school trip.

When the students exit the station, they will ascend to street level in an elevator.

Student A says that the passengers in the lift will gain gravitational potential energy as they travel in the lift.

Student B says that they will not gain gravitational potential energy, because they are below ground level.

State which student is correct and explain your answer.

2b5 marks

Higher Tier Only

The Tube station was designed to maximise efficiency.

The station has an upward-sloping track at its entrance and a downward-sloping track at its exit.

The driver uses breaks to stop the train and uses a motor to make the train move away.

Explain how the design of the station increases the efficiency of the trains. Use ideas about work done in your answer.

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3a1 mark

Which of the following is the correct efficiency equation in terms of work done?

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Efficiency space equals fraction numerator space wasted space work space done over denominator total space work space done end fraction  square
Efficiency space equals fraction numerator space useful space work space done over denominator wasted space work space done end fraction square
Efficiency space equals fraction numerator space useful space work space in over denominator total space work space out end fraction  square
Efficiency space equals fraction numerator space useful space work space out over denominator total space work space in end fraction  square
3b3 marks

The efficiency of an electric motor is 80 %.

When lifting a load, the amount of energy wasted is 100 J.

Calculate the useful work done (W) by the motor.

   

   

Useful work done = .................................... J

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