5.4 forces and motion - standard demand - qs

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5.4 Forces and motion - Standard demand – Questions

Q1. A group of students investigated how the acceleration of a trolley depends on the angle of a ramp.

Figure 1 shows the apparatus.

Figure 1

The students released the trolley from the top of the ramp.

The light gates were attached to a data logger.

The data logger calculated the velocity of the trolley at each light gate.

(a) When the students released the trolley they did not push it.

Suggest why this is important.

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___________________________________________________________________ (1)

(b) Measure angle X shown in Figure 1.

X = ____________________ degrees (1)

The students repeated the experiment with different angles of the ramp.

(c) Suggest how the students could increase the angle of the ramp.

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___________________________________________________________________ (1)

Figure 2 shows the velocity-time graph for the trolley when the angle of the ramp was X.

Figure 2

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(d) The gradient of the line represents the acceleration of the trolley.

Determine the acceleration of the trolley in Figure 2.

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Acceleration = ____________________ m/s2

(3)

(e) What does the area under the graph in Figure 2 represent?

Tick one box.

Average velocity

Maximum velocity

Time taken

Total distance travelled

(1)

(f) The students repeated the measurements for each angle several times.

Suggest how the students could check the repeatability of the data.

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___________________________________________________________________ (2)

(g) The trolley was released from a point 0.34 m above the surface the ramp was resting on.

The mass of the trolley was 0.75 kg

Gravitational field strength = 9.8 N/kg

Calculate the gravitational potential energy of the trolley before it was released.

Use the equation:

gravitational potential energy = mass × gravitational field strength × height

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Gravitational potential energy = ____________________ J (2)

(Total 11 marks)

Q2. Four students tested their reaction times using a computer program.

When a green light appeared on the screen the students had to press a key.

Table 1 shows their results.

Table 1

Student Reaction time in s Mean

reaction time in s Test 1 Test 2 Test 3

Boy 1 0.28 0.27 0.26 0.27

Boy 2 0.28 0.47 0.22 0.29

Girl 1 0.31 0.29 0.27 0.29

Girl 2 0.32 0.30 0.29 0.30

(a) What is meant by ‘reaction time’ in this experiment?

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___________________________________________________________________ (1)

(b) Boy 2 had an anomalous result in Test 2.

Suggest a reason why.

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(c) Give one conclusion that can be made from the results in Table 1.

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___________________________________________________________________ (1)

(d) Suggest further evidence that you could collect to support your conclusion.

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(e) Reaction time is important at the start of a race.

Table 2 shows the time taken by a boy to run different distances.

Table 2

Distance in m Time in s

100 12.74

200 25.63

800 139.46

Reaction time is more important in a 100 m race than in an 800 m race.

Explain why.

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(f) Two girls, A and B, ran an 800 m race.

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The figure below shows how the distance changed with time.

Compare the motion of runners A and B.

Include data from the figure above.

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(Total 12 marks)

Q3. This question is about speed.

(a) What is a typical value for the speed of sound?

Tick one box.

3.3 m / s

3.3 × 102 m / s

3.3 × 103 m / s

3.3 × 106 m / s

(1)

(b) Figure 1 shows a distance–time graph of a car.

Figure 1

Explain what Figure 1 shows about the motion of the car between point A and point E.

You should use values from Figure 1 in your answer.

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(c) The kinetic energy of a moving car depends on the car’s mass and speed.

Write down the equation that links kinetic energy, mass and speed.

___________________________________________________________________ (1)

(d) A car has a mass of 1 650 kg.

The table below shows the kinetic energy of the car moving at 11 m / s.

Mass of car in kg Speed in m / s Kinetic energy in J

1 650 11 99 825

1 650 30

Calculate the missing value in the table above.

Give your answer in kilojoules (kJ).

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___________________________________________________________________

Kinetic energy = _________________ kJ (2)

(e) A man is driving his car at a constant speed on a wet road.

He sees a fallen tree on the wet road and tries to stop quickly to prevent an accident.

Figure 2

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© Paul-Briden/iStock/Thinkstock

Explain why the man may not be able to stop in time.

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(Total 14 marks)

Q4. The diagram shows a water butt used to collect rainwater.

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A tap allows water to be collected from the water butt in a watering can.

(a) If the tap was placed higher up on the water butt, what difference would it make to the rate of flow of water from the tap?

Explain your answer.

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___________________________________________________________________ (2)

(b) A hosepipe is now attached to the tap. The hosepipe takes water to where it is needed.

A gardener did an investigation to see how the rate of flow of water through a hosepipe, from a water butt, varies with the length of the hosepipe.

His results are shown in below table.

Length of hosepipe in

metres

Water collected in 10 seconds in

cm3

2.0 500

3.0 500

4.0 500

5.0 500

10.0 250

15.0 170

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(i) What conclusions can you make based on the results in the table above?

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______________________________________________________________ (2)

(ii) Suggest further readings that should be taken to improve the investigation.

Give reasons for your answers.

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(c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

You are provided with a water butt and lengths of hosepipe of different diameter.

Describe how you would investigate how the rate of flow of water through a hosepipe varies with the diameter of the hosepipe.

In your description you should include: • any additional equipment that you would use

• any measurements you would make using the equipmentz

• any variables that need to be controlled and how this would be achieved.

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(Total 14 marks)

Q5. An investigation was carried out to show how thinking distance, braking distance and stopping distance are affected by the speed of a car.

The results are shown in the table.

Speed in metres

per second

Thinking distance in metres

Braking distance in

metres

Stopping distance in metres

10 6 6 12

15 9 14 43

20 12 24 36

25 15 38 53

30 18 55 73

(a) Draw a ring around the correct answer to complete each sentence.

As speed increases, thinking distance

decreases.

increases.

stays the same.

As speed increases, braking distance

decreases.

increases.

stays the same.

(2)

(b) One of the values of stopping distance is incorrect.

Draw a ring around the incorrect value in the table.

Calculate the correct value of this stopping distance.

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Stopping distance = ________________ m (2)

(c) (i) Using the results from the table, plot a graph of braking distance against speed.

Draw a line of best fit through your points.

Speed in metres per second (3)

(ii) Use your graph to determine the braking distance, in metres, at a speed of 22 m / s.

Braking distance = ________________ m (1)

(d) The speed–time graph for a car is shown below.

While travelling at a speed of 35 m / s, the driver sees an obstacle in the road at time t = 0. The driver reacts and brakes to a stop.

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Time in seconds

(i) Determine the braking distance.

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Braking distance = ________________ m (3)

(ii) If the driver was driving at 35 m / s on an icy road, the speed–time graph would be different.

Add another line to the speed–time graph above to show the effect of travelling at 35 m / s on an icy road and reacting to an obstacle in the road at time t = 0.

(3)

(e) A car of mass 1200 kg is travelling with a velocity of 35 m / s.

(i) Calculate the momentum of the car.

Give the unit.

______________________________________________________________

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Momentum = _____________________ (3)

(ii) The car stops in 4 seconds.

Calculate the average braking force acting on the car during the 4 seconds.

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Force = ________________ N (2)

(Total 19 marks)

Q6. The diagram shows a boat pulling a water skier.

(a) The arrow represents the force on the water produced by the engine propeller. This force causes the boat to move.

Explain why.

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___________________________________________________________________ (2)

(b) The boat accelerates at a constant rate in a straight line. This causes the velocity of the water skier to increase from 4.0 m/s to 16.0 m/s in 8.0 seconds.

(i) Calculate the acceleration of the water skier and give the unit.

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Acceleration = _________________________ (3)

(ii) The water skier has a mass of 68 kg.

Calculate the resultant force acting on the water skier while accelerating.

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Resultant force = _________________________ N (2)

(iii) Draw a ring around the correct answer to complete the sentence.

The force from the boat pulling the water skier forwards

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less than

will be the same as the answer to part (b)(ii).

greater than

Give the reason for your answer.

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______________________________________________________________ (2)

(Total 9 marks)

Q7. (a) A car is being driven along a straight road. The diagrams, A, B and C, show the

horizontal forces acting on the moving car at three different points along the road.

Describe the motion of the car at each of the points, A, B and C.

(3)

(b) The diagram below shows the stopping distance for a family car, in good condition, driven at 22 m/s on a dry road. The stopping distance has two parts.

(i) Complete the diagram below by adding an appropriate label to the second part of the stopping distance.

_______________________________

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_______________________________ (1)

(ii) State one factor that changes both the first part and the second part of the stopping distance.

______________________________________________________________ (1)

(c) The front crumple zone of a car is tested at a road traffic laboratory. This is done by using a remote control device to drive the car into a strong barrier. Electronic sensors are attached to the dummy inside the car.

(i) At the point of collision, the car exerts a force of 5000 N on the barrier.

State the size and direction of the force exerted by the barrier on the car.

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______________________________________________________________ (1)

(ii) Suggest why the dummy is fitted with electronic sensors.

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______________________________________________________________ (1)

(iii) The graph shows how the velocity of the car changes during the test.

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Use the graph to calculate the acceleration of the car just before the collision with the barrier.

Show clearly how you work out your answer, including how you use the graph, and give the unit.

______________________________________________________________

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Acceleration = ______________________________ (3)

(Total 10 marks)

Q8. (a) The diagram shows the forces acting on a parachutist in free fall.

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The parachutist has a mass of 75 kg.

Calculate the weight of the parachutist.

gravitational field strength = 10 N/kg

Show clearly how you work out your answer and give the unit.

___________________________________________________________________

___________________________________________________________________

Weight = __________________________ (3)

(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

The graph shows how the vertical velocity of a parachutist changes from the moment the parachutist jumps from the aircraft until landing on the ground.

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Using the idea of forces, explain why the parachutist reaches a terminal velocity and why opening the parachute reduces the terminal velocity.

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(c) A student wrote the following hypothesis.

‘The larger the area of a parachute, the slower a parachutist falls.’

To test this hypothesis the student made three model parachutes, A, B and C, from one large plastic bag. The student dropped each parachute from the same height and timed how long each parachute took to fall to the ground.

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(i) The height that the student dropped the parachute from was a control variable.

Name one other control variable in this experiment.

______________________________________________________________ (1)

(ii) Use the student’s hypothesis to predict which parachute, A, B or C, will hit the ground first.

Write your answer in the box.

Give a reason for your answer.

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______________________________________________________________ (2)

(Total 12 marks)

Q9. (a) A person takes their dog for a walk.

The graph shows how the distance from their home changes with time.

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Which part of the graph, A, B, C or D, shows them walking the fastest?

Write your answer in the box.

Give the reason for your answer.

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___________________________________________________________________ (2)

(b) During the walk, both the speed and the velocity of the person and the dog change.

How is velocity different from speed?

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(Total 3 marks)

Q10. (a) The diagram shows the horizontal forces acting on a swimmer.

(i) The swimmer is moving at constant speed. Force T is 120 N.

What is the size of force D?

_________________________ N (1)

(ii) By increasing force T to 140 N, the swimmer accelerates to a higher speed.

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Calculate the size of the initial resultant force acting on the swimmer.

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Initial resultant force = _________________________ N (1)

(iii) Even though the swimmer keeps the force T constant at 140 N, the resultant force on the swimmer decreases to zero.

Explain why.

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______________________________________________________________ (3)

(b) A sports scientist investigated how the force exerted by a swimmer’s hands against the water affects the swimmer’s speed. The investigation involved 20 males and 20 females swimming a fixed distance. Sensors placed on each swimmer’s hands measured the force 85 times every second over the last 10 metres of the swim. The measurements were used to calculate an average force. The average speed of each swimmer over the last 10 metres of the swim was also measured.

The data from the investigation is displayed in the graph.

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(i) What was the dependent variable in this investigation?

______________________________________________________________ (1)

(ii) Explain one advantage of measuring the force 85 times every second rather than just once or twice every second.

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______________________________________________________________ (2)

(iii) Give one way in which the data for the male swimmers is different from the data for the female swimmers.

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(iv) Considering only the data from this investigation, what advice should a swimming coach give to swimmers who want to increase their average speed?

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(Total 10 marks)

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Q11. A cyclist travelling along a straight level road accelerates at 1.2 m/s2 for 5 seconds. The mass of the cyclist and the bicycle is 80 kg.

(a) Calculate the resultant force needed to produce this acceleration.

Show clearly how you work out your answer and give the unit.

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Resultant force = ______________________ (3)

(b) The graph shows how the velocity of the cyclist changes with time.

(i) Complete the following sentence.

The velocity includes both the speed and the _____________ of the cyclist. (1)

(ii) Why has the data for the cyclist been shown as a line graph instead of a bar chart?

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______________________________________________________________ (1)

(iii) The diagrams show the horizontal forces acting on the cyclist at three different speeds. The length of an arrow represents the size of the force.

A

B

C

Which one of the diagrams, A, B or C, represents the forces acting when the cyclist is travelling at a constant 9 m/s?

______________________________________________________________

Explain the reason for your choice.

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______________________________________________________________ (3)

(Total 8 marks)

Q12. (a) The diagram shows a steel ball-bearing falling through a tube of oil.

The forces, L and M, act on the ball-bearing.

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What causes force L?

___________________________________________________________________ (1)

(b) The distance – time graph represents the motion of the ball-bearing as it falls through the oil.

(i) Explain, in terms of the forces, L and M, why the ball-bearing accelerates at first but then falls at constant speed.

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______________________________________________________________

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(ii) What name is given to the constant speed reached by the falling ball-bearing?

______________________________________________________________ (1)

(iii) Calculate the constant speed reached by the ball-bearing.

Show clearly how you use the graph to work out your answer.

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Speed = ______________________________ m/s (2)

(Total 7 marks)

Q13. (a) A car driver takes a short time to react to an emergency before applying the brakes.

The distance the car will travel during this time is called the ‘thinking distance’.

The graph shows how the thinking distance of a driver depends on the speed of the car.

(i) What is the connection between thinking distance and speed?

______________________________________________________________ (1)

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(ii) Many people drive while they are tired.

Draw a new line on the graph to show how thinking distance changes with speed for a tired driver.

(1)

(iii) The graph was drawn using data given in the Highway Code.

Do you think that the data given in the Highway Code is likely to be reliable?

Draw a ring around your answer.

Yes No Maybe

Give a reason for your answer.

______________________________________________________________

______________________________________________________________ (1)

(b) The distance a car travels once the brakes are applied is called the ‘braking distance’.

(i) What is the relationship between thinking distance, braking distance and stopping distance?

______________________________________________________________ (1)

(ii) State two factors that could increase the braking distance of a car at a speed of 15 m/s.

1. ____________________________________________________________

2. ____________________________________________________________ (2)

(Total 6 marks)

Q14. (a) The arrows in the diagram represent the size and direction of the forces on a space

shuttle, fuel tank and booster rockets one second after launch. The longer the arrow the bigger the force.

Thrust force

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Weight of shuttle, fuel tanks and booster rockets plus air resistance

(i) Describe the upward motion of the space shuttle one second after launch.

______________________________________________________________ (1)

(ii) By the time it moves out of the Earth’s atmosphere, the total weight of the space shuttle, fuel tank and booster rockets has decreased and so has the air resistance.

How does this change the motion of the space shuttle? (Assume the thrust force does not change).

______________________________________________________________ (1)

(b) The space shuttle takes 9 minutes to reach its orbital velocity of 8100 m/s.

(i) Write down the equation that links acceleration, change in velocity and time taken.

______________________________________________________________ (1)

(ii) Calculate, in m/s2, the average acceleration of the space shuttle during the first 9 minutes of its flight. Show clearly how you work out your answer.

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______________________________________________________________

average acceleration = _______________________ m/s2

(2)

(iii) How is the velocity of an object different from the speed of an object?

______________________________________________________________

______________________________________________________________ (1)

(Total 6 marks)

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Q15. (a) The diagram shows the horizontal forces that act on a moving motorbike.

(i) Describe the movement of the motorbike when force A equals force B.

______________________________________________________________

______________________________________________________________ (2)

(ii) What happens to the speed of the motorbike if force B becomes smaller than force A?

______________________________________________________________ (1)

(b) The graph shows how the velocity of a motorbike changes when it is travelling along a straight road.

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(i) What was the change in velocity of the motorbike in the first 5 seconds?

______________________________________________________________ (1)

(ii) Write down the equation which links acceleration, change in velocity and time taken.

______________________________________________________________ (1)

(iii) Calculate the acceleration of the motorbike during the first 5 seconds. Show clearly how you work out your answer and give the unit.

______________________________________________________________

______________________________________________________________

Acceleration = _______________________ (3)

(c) A car is travelling on an icy road.

Describe and explain what might happen to the car when the brakes are applied.

___________________________________________________________________

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___________________________________________________________________

___________________________________________________________________ (2)

(d) Name three factors, other than weather conditions, which would increase the overall stopping distance of a vehicle.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

3. _________________________________________________________________

___________________________________________________________________ (3)

(Total 13 marks)

Q16. The apparatus shown is used to compare the motion of a coin with the motion of a piece of paper as they both fall.

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(a) When the tube is filled with air the coin falls faster than the piece of paper. Why?

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___________________________________________________________________ (1)

(b) The air in the tube is removed by the vacuum pump. The tube is turned upside down. State two ways in which the motion of the coin and piece of paper will change compared to when there was air in the tube.

1. _________________________________________________________________

___________________________________________________________________

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2. _________________________________________________________________

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___________________________________________________________________ (2)

(Total 3 marks)

Q17. A cyclist goes on a long ride. The graph shows how the distance travelled changes with time during the ride.

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(i) Between which two points on the graph was the cyclist moving at the fastest speed?

___________________________________________________________________ (1)

(ii) State one way cyclists can reduce the air resistance acting on them.

___________________________________________________________________

___________________________________________________________________ (1)

(iii) How long did the cyclist stop and rest?

___________________________________________________________________ (1)

(iv) Write down the equation which links distance, speed and time.

___________________________________________________________________ (1)

(v) Calculate, in km/hr, the average speed of the cyclist while moving.

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Average speed = _______________ km/hr (3)

(Total 7 marks)

Q18. When a car driver has to react and apply the brakes quickly, the car travels some distance before stopping. Part of this distance is called the “thinking distance”. This is how far the

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car travels while the driver reacts to a dangerous situation.

The table below shows the thinking distance (m) for various speeds (km/h).

Thinking distance (m) 0 9 12 15

Speed (km/h) 0 48 64 80

(a) On the graph paper below, draw a graph of the thinking distance against speed.

(2)

(b) Describe how thinking distance changes with speed.

___________________________________________________________________

___________________________________________________________________ (1)

(c) The time the driver spends thinking before applying the brakes is called the “thinking time”.

A driver drank two pints of lager. Some time later the thinking time of the driver was measured as 1.0 seconds.

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(i) Calculate the thinking distance for this driver when driving at 9 m/s.

______________________________________________________________

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Answer ______________________ m (1)

(ii) A speed of 9 m/s is the same as 32 km/h. Use your graph to find the thinking distance at 32 km/h for a driver who has not had a drink.

______________________________________________________________

Answer ______________________ m (1)

(iii) What has been the effect of the drink on the thinking distance of the driver?

______________________________________________________________

______________________________________________________________ (1)

(Total 6 marks)

Q19. (a) When a car is driven efficiently the engine gives a constant forward pull on the car

as the car accelerates to its maximum speed. During this time frictional forces and air resistance oppose the forward motion of the car. The sketch graphs below show how the car’s speed increases when only the driver is in the car, and when the driver has a passenger in the car.

(i) How does the acceleration of the car change with time?

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______________________________________________________________

______________________________________________________________ (1)

(ii) What conclusion can be made about the resultant (net) forward force on the car as its speed increases?

______________________________________________________________

______________________________________________________________ (1)

(ii) On the graph, draw a line to show how you would expect the car’s speed to vary if it carried three passengers.

(1)

(b) The manufacturer of a family car gave the following information.

Mass of car 950g

The car will accelerate from 0 to 33 m/s in 11 seconds.

(i) Calculate the acceleration of the car during the 11 seconds.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Answer ___________________________ (2)

(ii) Calculate the force needed to produce this acceleration.

______________________________________________________________

______________________________________________________________

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Answer _________________ N (2)

(iii) The manufacturer of the car claims a top speed of 110 miles per hour. Explain why there must be a top speed for any car.

______________________________________________________________

______________________________________________________________ (2)

(Total 9 marks)

Q20. (a) The diagram below shows a moving tractor. The forward force from the engine

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exactly balances the resisting forces on the tractor.

(i) Describe the motion of the tractor.

______________________________________________________________

(ii) The tractor comes to a drier part of the field where the resisting forces are less. If the forward force from the engine is unchanged how, if at all, will the motion of the tractor be affected?

______________________________________________________________

______________________________________________________________ (3)

(b) Two pupils are given the task of finding out how fast a tractor moves across a field. As the tractor starts a straight run across the field the pupils time how long it takes to pass a series of posts which are forty metres apart. The results obtained are shown in the table below.

Distance travelled (m) 0 40 80 120 160 200

Time taken (s) 0 8 16 24 32 40

(i) Draw a graph of distance travelled against time taken using the axes on the graph below. Label your graph line A.

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(2)

(ii) Calculate the speed of the tractor.

______________________________________________________________

______________________________________________________________ (3)

(c) In another, wetter field there is more resistance to the movement of the tractor. It now travels at 4 m/s.

(i) Calculate the time needed to travel 200m.

______________________________________________________________

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(ii) On the graph in part (b) draw a line to represent the motion of the tractor across the second field. Label this line B.

(4)

(d) On a road the tractor accelerates from rest up to a speed of 6 m/s in 15 seconds.

Calculate the acceleration of the tractor.

___________________________________________________________________

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___________________________________________________________________

_______________________________________ Acceleration = ___________ m/s2

(3) (Total 15 marks)

Q21. Below is a distance-time graph for part of a train journey. The train is travelling at a constant speed.

(a) Use the graph to find

(i) how far the train travels in 2 minutes __________ km.

(ii) how long it takes the train to travel a distance of 10 kilometres

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________ minutes. (2)

(b) Calculate the speed of the train.

___________________________________________________________________

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___________________________________________________________________ (4)

(Total 6 marks)

Q22. A sky-diver jumps from a plane.

The sky-diver is shown in the diagram below.

(a) Arrows X and Y show two forces acting on the sky-diver as he falls.

(i) Name the forces X and Y.

X _____________________________

Y _____________________________ (2)

(ii) Explain why force X acts in an upward direction.

______________________________________________________________

______________________________________________________________ (1)

(iii) At first forces X and Y are unbalanced.

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Which of the forces will be bigger? ____________________ (1)

(iv) How does this unbalanced force affect the sky-diver?

______________________________________________________________

______________________________________________________________ (2)

(b) After some time the sky-diver pulls the rip cord and the parachute opens.

The sky-diver and parachute are shown in the diagram below.

After a while forces X and Y are balanced.

Underline the correct answer in each line below.

Force X has

increased / stayed the same / decreased.

Force Y has

increased / stayed the same / decreased.

The speed of the sky-diver will

increase / stay the same / decrease. (3)

(c) The graph below shows how the height of the sky-diver changes with time.

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(i) Which part of the graph, AB, BC or CD shows the sky-diver falling at a constant speed?

________________________ (1)

(ii) What distance does the sky-diver fall at a constant speed?

Distance _______________ m (1)

(iii) How long does he fall at this speed?

Time __________________ s (1)

(iv) Calculate this speed.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Speed _______________ m/s

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(2) (Total 14 marks)

Q23. A hot air balloon called Global Challenger was used to try to break the record for travelling round the world. The graph shows how the height of the balloon changed during the flight.

The balloon took off from Marrakesh one hour after the burners were lit and climbed rapidly.

(a) Use the graph to find:

(i) the maximum height reached.

Maximum height _______________ metres.

(ii) the total time of the flight.

Total time ______________________ hours. (2)

(b) Several important moments during the flight are labelled on the graph with the letters A, B, C, D, E and F. At which of these moments did the following happen?

(i) The balloon began a slow controlled descent to 2500 metres.

____________

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(ii) The crew threw out all the cargo on board in order to stop a very rapid descent.

____________

(iii) The balloon started to descend from 9000 metres.

____________ (3)

(Total 5 marks)

Q24. When a bungee-jump is made the jumper steps off a high platform. An elastic cord from the platform is tied to the jumper. The diagram below shows different stages in a bungee-jump. Forces A, B and C are forces acting on the jumper at each stage.

moving down moving down moving down

large acceleration small acceleration slowing acceleration

diagram X diagram Y diagram Z

(a) Name force A.

___________________________________________________________________ (1)

(b) The motion of the jumper is shown in the diagrams. By comparing forces A, B and C, state how the motion is caused in:

(i) diagram X;

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______________________________________________________________

(ii) diagram Y;

______________________________________________________________

(iii) diagram Z.

______________________________________________________________ (3)

(c) The table gives results for a bungee cord when it is being stretched.

STRETCHING FORCE (N) 100 200 400 600 800

LENGTH OF CORD (m) 20 24 32 40 48

(i) Plot a graph of these results on the graph paper.

(3)

(ii) Use the graph to find the length of the cord before it was stretched.

Length __________ m (1)

(Total 8 marks)

Q25.

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Five forces, A, B, C, D and E act on the van.

(a) Complete the following sentences by choosing the correct forces from A to E.

Force ________ is the forward force from the engine.

Force ________ is the force resisting the van’s motion. (1)

(b) The size of forces A and E can change. Complete the table to show how big force A is compared to force E for each motion of the van. Do this by placing a tick in the correct box. The first one has been done for you.

MOTION OF VAN FORCE A SMALLER THAN FORCE E

FORCE A EQUAL TO FORCE E

FORCE A BIGGER THAN FORCE E

Not moving

Speeding up

Constant speed

Slowing down

(3)

(c) When is force E zero?

___________________________________________________________________ (1)

(d) The van has a fault and leaks one drop of oil every second. The diagram below shows the oil drops left on the road as the van moves from W to Z.

Describe the motion of the van as it moves from:

W to X _________________________________________________________

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X to Y _________________________________________________________

Y to Z _________________________________________________________ (3)

(e) The driver and passengers wear seatbelts. Seatbelts reduce the risk of injury if the van stops suddenly.

backwards downwards force forwards mass weight

Complete the following sentences, using words from the list above, to explain why the risk of injury is reduced if the van stops suddenly.

A large ____________________ is needed to stop the van suddenly.

The driver and passengers would continue to move ____________________ .

The seatbelts supply a ____________________ force to keep the driver and

passengers in their seats. (3)

(Total 11 marks)

Q26. The graph shows changes in the velocity of a racing car.

(a) Describe the motion of the racing car during:

(i) the period labelled W; ____________________________________________

______________________________________________________________ (1)

(ii) the period labelled Y. ____________________________________________

______________________________________________________________ (1)

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(b) Calculate the acceleration of the racing car during the period labelled X. Show clearly how you work out your answer and give the unit.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Acceleration = _______________________ (4)

(Total 6 marks)

Q27. A car travels along a level road at 20 metres per second.

(a) Calculate the distance travelled by the car in 4 seconds.

(Show your working.)

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (3)

(b) When the brake pedal of the car is pushed, brake pads press against very hard steel discs.

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The force of friction between the brake pads and the steel discs gradually stops the car.

What two effects does using the brakes have on the brake pads and wheel discs?

1. _________________________________________________________________

2. _________________________________________________________________ (3)

(Total 6 marks)

Q28. A sky-diver steps out of an aeroplane.

After 10 seconds she is falling at a steady speed of 50m/s.

She then opens her parachute.

After another 5 seconds she is once again falling at a steady speed.

This speed is now only 10m/s.

(a) Calculate the sky-diver’s average acceleration during the time from when she opens her parachute until she reaches her slower steady speed. (Show your working.)

___________________________________________________________________

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___________________________________________________________________

___________________________________________________________________ (3)

(b) Explain, as fully as you can:

(i) why the sky-diver eventually reaches a steady speed (with or without her parachute).

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________ (3)

(ii) why the sky-diver’s steady speed is lower when her parachute is open.

______________________________________________________________ (1)

(c) The sky‑diver and her equipment have a total mass of 75kg. Calculate the gravitational force acting on this mass. (Show your working.)

___________________________________________________________________

___________________________________________________________________

Answer ____________________ N (1)

(Total 8 marks)

Q29. The graph shows the speed of a runner during an indoor 60 metres race.

(a) Choose words from this list to complete the sentences below.

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moving at a steady speed slowing down

speeding up stopped

Part A of the graph shows that the runner is _______________________________

Part B of the graph shows that the runner is _______________________________

Part C of the graph shows that the runner is _______________________________ (3)

(b) Calculate the acceleration of the runner during the first four seconds. (Show your working.)

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (3)

(Total 6 marks)

Q30. The diagram shows a shuttlecock that is used for playing badminton.

The shuttlecock weighs very little. When you drop it from a height of a few metres, it accelerates at first but soon reaches a steady speed.

Explain, as fully as you can:

(a) why the shuttlecock accelerates at first,

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(b) why the shuttlecock reaches a steady speed.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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___________________________________________________________________ (3)

(Total 5 marks)

Q31. A child goes out to visit a friend. The graph shows the child’s journey.

(a) Calculate the child’s average speed for the whole journey. [Show your working and give the units in your answer.]

___________________________________________________________________

___________________________________________________________________ (3)

(b) How many times faster is the child travelling in the first part of the journey than in the final part of the journey? [You should show how you obtained your answer.]

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(Total 5 marks)

5.4 forces and motion - standard demand - qs

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