Acceleration

Two drivers race their cars in a straight line over a distance of 400 metres.

Figure 5 shows the cars.

Figure 6 shows a distance-time graph for one car in the race.

When was the car travelling at a constant speed?

Give a reason for your answer.

Tick () one box.

Between 2 seconds and 3 seconds

Between 3 seconds and 4 seconds

Between 4 seconds and 5 seconds

The two horizontal forces acting on the car were a driving force and air resistance.

How did the driving force compare with the air resistance when the car moved at a constant speed?

Give a reason for your answer.

Tick () one box.

The driving force was less than air resistance.

The driving force was the same size as air resistance.

The driving force was greater than air resistance.

At the end of the race, the driver applies the brakes and opens a parachute to decelerate the car.

Figure 7 shows one of the cars at the end of the race.

Why may it be dangerous for a car to have a very large deceleration?

Tick () one box.

The car engine may overheat.

The car will stop in a short distance.

The driver may lose control of the car.

Figure 17 shows a rugby player running with a rugby ball.

Use the Physics Equations Sheet to answer questions 08.1 and 08.2.

Which equation links distance (s), speed (v) and time (t)?

Tick () one box.

The rugby player travels a distance of 44 m in a time of 5.0 s.

Calculate the mean speed of the rugby player.

The rugby player collides with another player and stops.

Use the Physics Equations Sheet to answer questions 08.3 and 08.4.

Which equation links acceleration (a), change in velocity (Δv) and time (t)?

Tick () one box.

a = Δv × t

The velocity of the rugby player changes from 6.0 m/s to 0.0 m/s in a time of 400 ms.

Calculate the deceleration of the rugby player.

Figure 18 shows a rugby player wearing a ‘mouthguard’.

Mouthguards reduce the risk of injury when rugby players collide.

A mouthguard has been invented that transmits data about the deceleration of a rugby player’s head during a collision.

A deceleration of 540 m/s² or more automatically alerts the team doctor at the side of the rugby pitch.

Use the Physics Equations Sheet to answer questions 08.5 and 08.6.

Which equation links acceleration (a), mass (m) and resultant force (F)?

Tick () one box.

F = m × a

The mass of a rugby player’s head is 3500 g.

During a collision the rugby player’s head has a deceleration of 540 m/s².

Calculate the resultant force on the rugby player’s head.

Give one advantage of using the new mouthguard when playing rugby compared with a mouthguard that does not transmit data.

Figure 1 shows a rugby player running with a rugby ball.

Use the Physics Equations Sheet to answer questions 01.1 and 01.2.

Which equation links distance (s), speed (v) and time (t)?

Tick () one box.

The rugby player travels a distance of 44 m in a time of 5.0 s.

Calculate the mean speed of the rugby player.

The rugby player collides with another player and stops.

Use the Physics Equations Sheet to answer questions 01.3 and 01.4.

Which equation links acceleration (a), change in velocity (Δv) and time (t)?

Tick () one box.

a = Δv × t

The velocity of the rugby player changes from 6.0 m/s to 0.0 m/s in a time of 400 ms.

Calculate the deceleration of the rugby player.

Figure 2 shows a rugby player wearing a ‘mouthguard’.

Mouthguards reduce the risk of injury when rugby players collide.

A mouthguard has been invented that transmits data about the deceleration of a rugby player’s head during a collision.

A deceleration of 540 m/s² or more automatically alerts the team doctor at the side of the rugby pitch.

Use the Physics Equations Sheet to answer questions 01.5 and 01.6.

Which equation links acceleration (a), mass (m) and resultant force (F)?

Tick () one box.

F = m × a

The mass of a rugby player’s head is 3500 g.

During a collision the rugby player’s head has a deceleration of 540 m/s².

Calculate the resultant force on the rugby player’s head.

Give one advantage of using the new mouthguard when playing rugby compared with a mouthguard that does not transmit data.

Two drivers raced their cars in a straight line over a distance of 400 metres.

Figure 8 shows the cars.

At the start of the race, one car accelerated from rest at 25 m/s².

The car moved 32 m while accelerating.

Calculate the final velocity of the car.

Use the Physics Equations Sheet.

At the end of the race, each driver applied the brakes and opened a parachute to decelerate the car.

Figure 9 shows one of the cars at the end of the race.

Explain how opening the parachute affects the deceleration of the car.

A student investigated how the acceleration of a glider on an air-track varies with the resultant force on the glider.

Figure 2 shows the apparatus used.

The air blower allows the glider to move along the air-track with almost no friction.

The resultant force acting on the glider is caused by the weight of the masses on the mass holder.

The datalogger calculates the velocity of the glider as the glider passes through the light gate.

This is the method used.

1. Release the glider from rest at the end of the air-track.

2. Record the velocity of the glider from the datalogger.

3. Repeat steps 1 and 2 two more times.

4. Record the resultant force acting on the glider.

5. Repeat steps 1 to 4 using different values of resultant force.

The student should enter the length of the card into the datalogger so that the datalogger can calculate velocity.

Which measuring instrument should the student use to measure the length of the card?

Tick () one box.

Measuring cylinder

Metre rule

Newtonmeter

Stopclock

The light gate measures the time taken for the card to pass through the light gate as 0.043 seconds.

What is the resolution of the light gate?

Tick () one box.

0.001 s
0.003 s
0.043 s

Table 1 shows the values for velocity when the resultant force was 0.50 N.

What is the range of the values for velocity shown in Table 1 ?

_ From ________________ m/s to ________________ m/s

The glider accelerated from rest for a distance of 0.98 m.

Calculate the acceleration of the glider when the velocity was 2.24 m/s.

Use the equation:

The student plotted a graph of the acceleration of the glider against the resultant force.

Figure 3 shows some of the results.

The student concluded:

‘The acceleration is directly proportional to the resultant force because the graph has a constant gradient.’

What other feature on a graph is needed to show a directly proportional relationship?

Tick () one box.

The line should curve upwards.

The line should have a negative gradient.

The line should pass through the origin.

Figure 3 is repeated below.

Calculate the gradient of the line in Figure 3.

Use the equation:

Figure 14 shows a velocity–time graph for a remote-controlled car.

Determine the acceleration of the car between 0 and 20 seconds.

Use the Physics Equations Sheet.

Determine the distance travelled by the car between 20 seconds and 45 seconds.

Use the Physics Equations Sheet.

How does the deceleration of the car compare with the acceleration of the car?

Use Figure 14.

Give one reason for your answer.

Tick (✓) one box.

The deceleration was greater than the acceleration.

The deceleration was the same as the acceleration.

The deceleration was less than the acceleration.

Another remote-controlled car travelled a distance of 80 m while accelerating from 0 m/s to 16 m/s.

Calculate the acceleration of this car.

Use the Physics Equations Sheet.

Figure 2 shows a velocity–time graph for a remote-controlled car.

Determine the acceleration of the car between 0 and 20 seconds.

Use the Physics Equations Sheet.

Determine the distance travelled by the car between 20 seconds and 45 seconds.

Use the Physics Equations Sheet.

How does the deceleration of the car compare with the acceleration of the car?

Use Figure 2.

Give one reason for your answer.

Tick (✓) one box.

The deceleration was greater than the acceleration.

The deceleration was the same as the acceleration.

The deceleration was less than the acceleration.

A skydiver jumped out of a helicopter.

Figure 4 shows a distance–time graph for the first 12 seconds of the skydiver’s fall.

How does Figure 4 show that the speed of the skydiver increased between 1 second and 6 seconds?

Tick (✓) one box.

The gradient decreases

The gradient stays the same

The gradient increases

What happened to the speed of the skydiver between 8 seconds and 12 seconds?

Use Figure 4.

Tick (✓) one box.

The speed decreased

The speed stayed the same

The speed increased

Determine the mean speed of the skydiver between 0 seconds and 12 seconds.

Use Figure 4 and the equation:

The forces acting on the skydiver during the fall were weight and air resistance.

What happened to the weight of the skydiver during the fall?

Tick (✓) one box.

Weight decreased

Weight stayed the same

Weight increased

What happened to the air resistance acting on the skydiver as the speed of the skydiver increased?

Tick (✓) one box.

Air resistance decreased

Air resistance stayed the same

Air resistance increased

The skydiver reached terminal velocity.

How did the forces acting on the skydiver compare at terminal velocity?

Tick (✓) one box.

Which of the following shows the velocity–time graph for the skydiver falling at terminal velocity?

Tick (✓) one box.

The skydiver decelerated when the parachute opened.

The initial resultant force on the skydiver was 960 N.

The mass of the skydiver was 64 kg.

Calculate the initial deceleration of the skydiver.

Use the equation:

Choose the unit from the box.

A skydiver jumped out of a helicopter.

Figure 8 shows a distance-time graph for the first 12 seconds after the skydiver jumped out of the helicopter.

Determine the speed of the skydiver between 8 and 12 seconds.

Use the Physics Equations Sheet.

Describe how the motion of the skydiver changed between 0 and 12 seconds.

Explain why the resultant force on the skydiver changed as the skydiver fell.

Which of the velocity–time graphs shows how the velocity of the skydiver changed after the parachute was opened?

Tick (✓) one box.

A student threw a ball vertically upwards into the air.

Figure 10 is a velocity-time graph of the ball’s motion after leaving the student’s hand until the ball reaches maximum height.

Air resistance has been ignored.

The maximum height is equal to the area between the line and the horizontal axis.

Calculate the maximum height reached by the ball.

Use Figure 10.

Calculate the gradient of the line in Figure 10.

Use the equation:

What does the gradient of the line in Figure 10 represent?

Tick (✓) one box.

The deceleration of the ball.

The distance travelled by the ball.

The speed of the ball.

In Figure 10 air resistance was ignored.

What would happen to the motion of the ball in Figure 10 if air resistance was included?

Tick (✓) two boxes.

The deceleration would be greater.

The final speed would be greater.

The initial kinetic energy would be less.

The initial velocity would be less.

The maximum height of the ball would be less.

The student threw a second ball vertically upwards into the air.

The maximum height reached by the second ball was 5.0 m.

The student caught the ball at the same height that the ball was thrown from.

The displacement of the ball is the straight-line distance between the start height and the end height.

What is the total distance the ball travels?

Tick (✓) one box.

0.0 m

5.0 m

10.0 m

What is the displacement of the ball when the student catches the ball?

Tick (✓) one box.

0.0 m

5.0 m

10.0 m

A student throws a ball vertically upwards in the air and catches the ball as it returns

Figure 18 is a velocity-time graph of the ball’s motion after leaving the student’s hand until the ball is caught.

Determine the maximum height the ball reaches.

The distance the ball travels when moving upwards is equal to the distance the ball travels when moving downwards.

Explain how Figure 18 shows that the two distances are equal.

Figure 18 does not include the effect that air resistance would have on the ball when it is in motion.

The graph in Figure 18 is a straight line with a constant gradient.

Explain why the gradient is constant.

Describe two ways the graph would change between 0.0 and 0.70 seconds if the effect of air resistance had been included.

Which displacement-time graph represents the ball’s motion after leaving the student’s hand until the ball is caught?

Tick (✓) one box.

The stopping distance of a vehicle depends on the thinking distance and the braking distance.

What is meant by ‘thinking distance’?

What would increase the thinking distance?

Tick (✓) two boxes.

Ice on the road surface

Poor condition of the brakes

The driver being tired

Using a mobile phone while driving

Wet weather

Figure 19 shows how the braking distance of a new car in 2020 compares with the braking distance of a new car in 1975.

The two cars had the same mass and were driven along a level road in sunny weather.

Explain the difference in braking distance between the two cars.

Use Figure 19.

The 2020 car was driven at a speed of 27 m/s. The brakes were applied until the car stopped.

The speed of the car decreased from 27 m/s to 0 m/s with a constant deceleration.

The mass of the car was 850 kg.

Determine the mean braking force on the car.

Use Figure 19.

Use the Physics Equations Sheet.

Figure 7 shows a student driving a bumper car at a theme park.

Figure 8 shows how the speed of the bumper car changed during a time of 20 seconds.

Estimate the distance travelled by the bumper car during the 20 seconds.

The bumper car motor has an efficiency of 80%.

The useful power output of the motor is 220 W.

Calculate the total power input to the motor.

Use the Physics Equations Sheet.

A bumper car collides with a stationary barrier and stops.

The student is wearing a seatbelt.

Explain how the seatbelt stops the student moving.

When the bumper car collided with the barrier, the bumper car came to a stop in a time of 600 ms.

The deceleration of the student was 2.0 m/s².

Calculate the initial velocity of the student.

Use the Physics Equations Sheet.

Figure 10 shows a cyclist on a straight, level road.

At one point in the journey the cyclist’s velocity changed from 5.0 m/s to 9.0 m/s in a time of 2.5 s.

Calculate the acceleration of the cyclist.

Use the equation:

Choose the unit from the box.

The maximum speed of the cyclist was 15 m/s.

The cyclist travelled at this speed for 60 s.

Calculate the distance travelled by the cyclist during this time.

Use the equation:

distance travelled = speed × time

The maximum speed of this cyclist is much higher than the typical mean speed of a cyclist.

What is the typical mean speed of a cyclist?

Tick (✓) one box.

1.5 m/s
3.0 m/s
6.0 m/s

Give two factors that would decrease the maximum speed of a cyclist on a journey.

At the end of the journey the cyclist decelerates from a speed of 15 m/s and stops.

The deceleration of the cyclist is 5 m/s².

Calculate the distance travelled while decelerating.

Use the Physics Equations Sheet.

Figure 5 shows a cyclist on a straight, level road.

The cyclist’s initial speed is zero.

The cyclist pushes on the pedals so that there is a constant forward force on the bike.

The force of air resistance increases as speed increases.

Explain why the speed of the cyclist reaches a maximum value.

The cyclist accelerates from 1.0 m/s to 5.0 m/s with an acceleration of 1.6 m/s².

Calculate the distance travelled during this acceleration.

In 2019 a cyclist broke a land speed record by cycling at a speed of 296 km/h.

Calculate the speed of the cyclist in m/s.

Figure 10 shows a girl inside a train which is moving to the left at a speed of 20 m/s

The girl is wearing inline skates.

The train is moving at a constant speed of 20 m/s

The train suddenly decelerates.

The girl continues to move with a speed of 20 m/s

Which of Newton’s laws is a correct explanation of this situation?

Tick (✓) one box.

Figure 11 shows a velocity-time graph for the train as it arrives at a station and stops.

Between which two times on Figure 11 is the train stationary?

Tick (✓) one box.

The train travels at a constant speed between 0 seconds and 5 seconds.

Determine the distance the train travels between 0 seconds and 5 seconds.

Use the equation:

distance travelled = speed × time

Between which two times on Figure 11 is the deceleration of the train the greatest?

Write down the equation which links acceleration (a), change in velocity (Δ v) and time taken (t).

Determine the acceleration of the train between 15 seconds and 20 seconds.

Write down the equation which links kinetic energy (E_k), mass (m) and speed (v).

At one point in the train’s journey the train’s speed was 6.0 m/s

At this point the kinetic energy of the train was 1 080 000 J

Calculate the mass of the train.

Figure 13 shows a girl inside a train. The girl is wearing inline skates.

The train is moving at a constant velocity. The girl is stationary relative to the train.

The girl is not touching the train walls.

The train suddenly decelerates.

Explain what will happen to the movement of the girl as the train suddenly decelerates.

Figure 14 shows a velocity-time graph for the train for part of its journey.

Write down the equation which links acceleration (a), change in velocity (Δ v) and time taken (t).

Determine the acceleration of the train between 5 seconds and 11 seconds.

Determine the total displacement of the train between 0 seconds and 25 seconds.

At a different point in the journey the train decelerates from a velocity of 40 m/s to a velocity of 15 m/s

Calculate the distance the train travels while decelerating.

Figure 15 shows part of the track for the train’s journey.

The train moves at a constant speed along this part of the track.

The train is accelerating.

Explain how the train can be accelerating while travelling at a constant speed.

An athlete trains to improve his fitness by walking, cycling and running.

What is a typical mean speed for a person walking?

Tick one box.

What is a typical mean speed for a person cycling?

Tick one box.

The athlete takes part in a race on a straight, horizontal running track.

Figure 6 shows the velocity-time graph for the athlete. A, B, C, D and E represent points in the race.

Determine the time taken for the athlete to move between points C and D.

Point E represents the end of the race.

After point E, the athlete has a constant deceleration.

The athlete stops 14 seconds after the start of the race.

Complete Figure 6 to show the motion of the athlete after point E.

Which section of the graph in Figure 6 shows the athlete moving at constant velocity?

Tick one box.

Which section of the graph in Figure 6 represents a part of the race where the resultant force on the athlete is zero?

Tick one box.

What does the area under a velocity-time graph represent?

Tick one box.

Write the equation which links acceleration, mass and resultant force.

In another race, the athlete had a constant acceleration during the first 3.2 seconds. His velocity increased from 0 m/s to 11.6 m/s

Calculate the acceleration of the athlete.

Use the equation:

An athlete takes part in a race on a straight, horizontal running track.

Figure 5 shows the velocity-time graph for the athlete during the race.

What is the main force that opposes the athlete’s forward motion?

Which section of the graph represents a part of the race where the resultant force on the athlete is zero?

Tick one box.

The athlete has a mass of 94.8 kg

Calculate the momentum of the athlete at a time of 6.0 s

Use Figure 5.

The acceleration is not constant from D to E.

Determine the acceleration at a time of 12.0 s

Use Figure 5.

Give the unit.

Figure 6 is a copy of Figure 5 to help you answer the following questions.

A second athlete starts the race at the same time as the first athlete.

The second athlete moves with a constant acceleration of 1.6 m/s² for the first 6.0 seconds of the race.

The first athlete travels further than the second athlete during the first 6.0 seconds.

Draw a line on Figure 6 to represent the motion of the second athlete for the first 6.0 seconds of the race.

Determine the extra distance travelled by the first athlete over the first 6.0 seconds of the race.

Use Figure 6.