Conservation of Energy (Edexcel GCSE Physics)

Exam Questions

1 hour9 questions
1a1 mark

Which are the correct units of energy?

square   A   N/m2

square   B   N/s

square   C   J

square   D   J/s

1b
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1 mark

Define what the term "closed" means when referring to a system.

1c
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1 mark

State the law of conservation of energy.

1d
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5 marks

Complete the equations for kinetic energy and gravitational potential energy (GPE).

Choose quantities from the box. 

Each quantity can be used once, more than once or not at all.

  

mass force speed
height gravitational field strength acceleration

  

     

kinetic space energy space equals space 1 half space cross times space........... space cross times space........... space squared

   

GPE space equals space........... space cross times space........... space cross times space...........

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2a
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1 mark

Figure 1 shows a toy car on a race track that travels around a vertical loop.

screenshot-2023-06-06-121736

Figure 1

At which point does the toy car have the most energy in its gravitational potential store?

square   A   

square   B   

square   C   

square   D   

2b
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1 mark

State the energy transfer taking place between position A and position B.

2c
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1 mark

The toy car has 1.5 J of energy in its gravitational potential store at position A. 

Assuming that energy losses are negligible, state the energy in the car's kinetic store at B.

2d
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3 marks

The car has a speed of 2.0 m/s at B.

Calculate the mass of the car.

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3a
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2 marks

A cyclist is riding along a straight, level road at a constant speed.

Complete the sentences with a suitable word or phrase.
  

As the cyclist rides along the road, energy in the .................................... energy store of the cyclist’s body decreases.

The cyclist continues at the same speed up a hill. The energy in the cyclist's .................................... store increases.

3b
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2 marks

The cyclist has a mass of 80 kg and is travelling at 5 m/s at the top of a hill.

Calculate the energy in their kinetic store at this exact moment.

  

  

energy in kinetic store = .................................... J

3c
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2 marks

They lose 8 000 J from their gravitational potential store by riding down the hill. The hill then flattens out.

Assuming the system is closed, calculate the amount of energy in the kinetic store of the cyclist at the foot of the hill.

  

  

energy in kinetic store .................................... J

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1a1 mark

Which of these is a non-renewable source of energy?


  A geothermal
  B natural gas
  C tidal
  D solar
1b2 marks
Explain why renewable sources provide an increasing fraction of the electricity supply for many countries.
1c6 marks

Electricity can be generated using a water turbine.

i)
Water gains kinetic energy by falling from the top of a dam.

Calculate the minimum height that 7.0 kg of water must fall to gain 1300 J of kinetic energy.

[3]

minimum height = ........................................................... m

ii)
As water enters the turbine at the bottom of the dam, the kinetic energy of 8.0 kg of moving water is 1100 J.

Calculate the speed of the moving water as it enters the turbine.

[3]

speed = .......................................................... m/s

1d3 marks

Moving air can be used to generate electricity using a wind turbine.

Figure 8 is a graph of kinetic energy against wind speed for a mass of moving air.

fig-8-ipho-1h-june18-qp-edexcel-gcse-physics
Figure 8

Just before the air reaches a wind turbine it has a wind speed of 15 m/s.

When the air has gone through the turbine it has a wind speed of 13 m/s.

As the air moves through the turbine some of the energy in its kinetic store is transferred to the turbine's kinetic store.

Use the graph to determine the percentage of the energy in the wind's kinetic store transferred to the turbine from the air.




percentage of energy transferred from the air's kinetic store = ......................... %

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2a4 marks

Figure 5 shows a way of projecting a small trolley up a sloping track.

fig-5-paper1h-june2019-edexcel-gcse-physics

Figure 5

When the button is pressed, a spring is released in P that projects the trolley up the track.
The trolley travels up the track, stops and then rolls back down.
The spring in P always exerts the same force when projecting the trolley.

A student investigates how the mass of the trolley affects the maximum vertical height, h, reached by the trolley.

State the measurements the student should make to complete the investigation.

You should make use of the equipment shown in Figure 5 and any other equipment that is needed.

2b3 marks

Figure 6 is a graph of the student’s results.

fig-6-paper1h-june2019-edexcel-gcse-physics

Figure 6

The student states that the energy transferred by the spring is the same each time it is used.

Use data from any two points on the graph in Figure 6 to support this statement.

2c3 marks

Describe how the student could extend the investigation to determine the average speed of the trolley as it rolls back down the track.

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3a3 marks

Figure 1 shows a person on a zip wire. The person's weight is 650 N.

zip-wire

Figure 1

The person has 15 000 J in their gravitational potential store at the top of the tower.

Determine the vertical height of the tower.

 

height = ................................... m

3b3 marks

The height of the zip rope at the end of the ride is 2.5 m above ground.

Determine the change in gravitational potential energy over the course of the zip rope ride.

 
 
 
change in gravitational potential energy =  .................................... J
3c2 marks

Determine the mass of the rider.

Give your answer to the nearest kg.

 
 
 
mass =  .................................... kg
3d4 marks

Determine the speed of the rider just before they reach the end of the zip rope.

Ignore any frictional forces.

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4a3 marks

Figure 1 shows a cyclist riding down an incline.

cyclist-incline

Figure 1

Use words from the box to complete the following sentences.
  
thermal chemical kinetic gravitational elastic

As the cyclist rides down the hill, the amount of energy in his .............................. store decreases.

As the cyclist accelerates, energy in his .............................. store increases.

When the cyclist uses his breaks to stop, energy is transferred to the .............................. store of the brake pads.

4b1 mark

The cyclist descends the hill without braking.

The hill the cyclist rode down has a vertical height of 23.5 m.

20 kJ of energy was transferred from the cyclist's gravitational potential energy store as he rode from the top of the hill to the bottom.

Determine the mass of the cyclist.

Give your answer to 3 significant figures.

   

   

mass of cyclist  = .................................... kg
4c4 marks
Calculate the maximum speed of the cyclist during his descent.

Ignore any energy losses.

Give your answer to 1 significant figure.

   

   

maximum speed = .................................... m/s
4d4 marks

In reality, the cyclist only achieved a maximum speed of 12 m/s.

Calculate the percentage efficiency of the cyclist. 

 
 
 
efficiency =  .................................... %

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5a3 marks

A small plastic ball is held at a height, h, above the ground.

The ball is released and takes 2.34 s to fall to the ground.

Calculate the distance the ball travelled during its fall. Ignore any energy losses.

Use the equation

t squared space equals space fraction numerator 2 h over denominator g end fraction
 
 
 
distance =  .................................... m
5b2 marks
Describe the energy transfer taking place as the ball is released and falls.
5c2 marks
The ball was dropped repeatedly from the same height, but the measured time taken was different for each repeat.

 

(i)
Suggest why the time measured was different for each repeat.
[1]
 
(ii)
Suggest how to improve the accuracy of the measurement.
[1]
5d5 marks

A different ball of mass 23 g is dropped from the same height.

(i)
Calculate the change in gravitational potential energy as the ball falls.
 [3]
 
 
change in gravitational potential energy = .................................... J
 
 
(ii)
State the energy transfer that occurs at the moment the ball hits the ground.
[2]

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6a
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2 marks

A student lifts a toy car from a bench and places the toy car at the top of a slope as
shown in Figure 2.

fig-2-paper1h-june2020-edexcel-gcse-physics

Figure 2

Describe an energy transfer that occurs when the student lifts the toy car from the bench and places the toy car at the top of the slope.

[2]

6b
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4 marks

The student lets the toy car roll down the slope.

Describe how the student could find, by experiment, the speed of the toy car at the bottom of the slope.

[4]

6c
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2 marks
c)
The student needs to develop the experiment to determine the loss in potential energy and the gain in kinetic energy as the toy car is rolling down the slope.

State the other measurements the student must make.

(2)

6d
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1 mark
d)
When the toy car rolls down the slope, some energy is transferred to the surroundings as thermal energy.

State how the student could calculate the amount of energy transferred to the surroundings.

(1)

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