Newton's laws of motion

Figure 1 shows a person about to dive from a high platform into a pool of water.

The person dived from the platform into the water.

The time taken between the person leaving the platform and entering the water was measured by four people.

The measurements were:

2.1 s 1.9 s 1.3 s 2.0 s

Which measurement is anomalous?

Tick () one box.

Air resistance acted on the person during the dive.

Figure 2 shows the person moving vertically downwards.

Which arrow on Figure 2 shows the direction of the air resistance acting on the person?

Tick () one box.

Air resistance is a contact force.

Which force is also a contact force?

Tick () one box.

What happened to the size of the air resistance force as the speed of the person increased?

After entering the water, the person decelerated for a time of 0.35 s.

The deceleration of the person was 60 m/s².

Calculate the change in velocity of the person.

Use the equation:

change in velocity = deceleration × time

The mass of the person was 75 kg.

Calculate the resultant force on the person when the deceleration was 60 m/s².

Use the equation:

resultant force = mass × deceleration

In a dog-sled race, a team of dogs pull on a rope attached to a sled.

Figure 12 shows a dog-sled team.

Use the Physics Equations Sheet to answer questions 06.1 and 06.2.

What equation links distance travelled, speed and time?

Tick () one box.

The longest dog-sled race in the world covers a distance of 1 500 000 m.

One team finished the race in a time of 670 000 s.

Calculate the average speed of this team during the race.

At the start of the race, 6 dogs pulled on the rope.

The average forward force on the sled from each dog was 370 N.

The backwards force on the sled from friction was 520 N.

Calculate the resultant force on the sled.

Figure 13 shows a distance–time graph for the sled at the start of the race.

What does the gradient of the graph in Figure 13 represent?

Later in the race, the sled moved at a constant speed along a flat, horizontal path.

What was the relationship between the size of the horizontal forces acting when the sled moved at a constant speed?

Tick () one box.

The rope exerted a force on the sled when the sled was moving.

What is the Newton’s Third Law pair to the force of the rope on the sled?

Tick () one box.

In a dog-sled race, a team of dogs pull on a rope attached to a sled.

Figure 1 shows a dog-sled team.

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

What equation links distance travelled, speed and time?

Tick () one box.

The longest dog-sled race in the world covers a distance of 1 500 000 m.

One team finished the race in a time of 670 000 s.

Calculate the average speed of this team during the race.

At the start of the race, 6 dogs pulled on the rope.

The average forward force on the sled from each dog was 370 N.

The backwards force on the sled from friction was 520 N.

Calculate the resultant force on the sled.

Figure 2 shows a distance–time graph for the sled at the start of the race.

What does the gradient of the graph in Figure 2 represent?

Later in the race, the sled moved at a constant speed along a flat, horizontal path.

What was the relationship between the size of the horizontal forces acting when the sled moved at a constant speed?

Tick () one box.

The rope exerted a force on the sled when the sled was moving.

What is the Newton’s Third Law pair to the force of the rope on the sled?

Tick () one box.

Figure 4 shows a person using a newtonmeter to measure the weight of a suitcase.

There is a pair of forces acting between the suitcase and the newtonmeter.

How does the force on the suitcase compare with the force on the newtonmeter?

Tick () one box.

Which sentence describes the directions in which the pair of forces act?

Tick () one box.

What is the weight of the suitcase shown on the newtonmeter in Figure 4 ?

Calculate the mass of the suitcase.

gravitational field strength = 9.8 N/kg

Use your answer from Question 02.3 and the equation:

The suitcase is loaded into an aeroplane. The aeroplane takes off and its height above the ground increases. The aeroplane then flies at a constant height.

Figure 5 shows how the gravitational field strength in the aeroplane varies for the first 25 minutes of the flight.

Describe how the weight of the suitcase will change during the first 25 minutes of the flight.

Use Figure 5.

Figure 8 shows a permanent magnet and two magnetic compasses.

The poles of the magnet are labelled X and Y.

The direction of the compass needle in compass A is shown.

Give the names of the poles labelled X and Y in Figure 8.

Draw an arrow on compass B in Figure 8 to show the direction of the magnetic field at that position.

Figure 9 shows security tags on some clothes in a shop.

Security tags can be detected if clothes are taken out of the shop with tags still attached.

The tags are attached to the clothes by pins made from a magnetic material.

A shop assistant can use a magnet to remove the pins.

Which of the following are magnetic materials?

Tick () two boxes.

Which of the following describes the force between a magnetic material and a magnet?

Tick () one box.

The shop assistant removes a security tag and drops the tag into a collecting bin.

As it falls, the tag accelerates at 9.8 m/s².

The mass of the tag is 0.030 kg.

Calculate the resultant force acting on the tag.

Use the equation:

resultant force = mass × acceleration

Figure 6 shows two magnets and a wire.

There is a current in the wire.

A force acts on the wire in Figure 6.

What is the direction of the force on the wire?

Tick () one box.

The length of the wire in the magnetic field between the magnets is 80 mm.

The current in the wire is 4.6 A.

The force on the wire is 0.092 N.

Calculate the magnetic flux density between the magnets.

Use the Physics Equations Sheet.

Give the unit.

Figure 7 shows an electromagnet close to a permanent magnet.

The electromagnet exerts a force on the permanent magnet.

The permanent magnet exerts an equal and opposite force on the electromagnet.

Which law is this an example of?

Tick () one box.

Give two changes to the electromagnet that would increase the force exerted on the permanent magnet.

Give two changes to the electromagnet that would reverse the direction of the force exerted on the permanent magnet.

A safety test was carried out to determine how the speed of a car affects the stopping distance of the car.

At the start of the test the car was moving slowly.

Then the car accelerated at 5.8 m/s² for 2.5 s.

The final velocity of the car was 20 m/s.

Calculate the initial velocity of the car.

Use the Physics Equations Sheet.

The reaction time of the driver was measured.

How can the reaction time of the driver be used to calculate the thinking distance?

The car was driven at a constant speed. The driver applied the maximum braking force, and the braking distance was measured.

The test was repeated at different speeds.

Figure 8 shows the results.

Which of the following gives the relationship between the speed and the braking distance?

Tick () one box.

During one test the brakes were applied with a force of 6250 N.

The deceleration of the car was 5.0 m/s².

The braking distance of the car was 14.4 m.

Determine the momentum of the car before the brakes were applied.

Use the Physics Equations Sheet.

Use Figure 8.

Momentum = kg m/s

Rockets have been developed so that people who are not trained astronauts can pay to travel to space.

Figure 9 shows the passenger module and the propulsion module of a rocket.

The propulsion module burns a large volume of fuel.

The rocket was initially stationary on the ground.

Then the rocket accelerated upwards until it reached a height of 40 km.

The constant acceleration of the rocket was 6.48 m/s².

Calculate the velocity of the rocket at a height of 40 km.

Use the Physics Equations Sheet.

Explain how the weight of the rocket changed as it accelerated upwards.

At a height of 40 km, the rocket stopped burning fuel.

The rocket continued upwards to its maximum height of 60 km.

Explain why the velocity of the rocket decreased between a height of 40 km and a height of 60 km.

At a height of 60 km the two modules of the rocket separated and the passenger module fell back to Earth.

Figure 10 shows the passenger module falling towards the Earth’s surface.

Using parachutes causes the passenger module to fall with a lower terminal velocity than if parachutes were not used.

Explain why the parachutes allow the passenger module to fall with a lower terminal velocity.

A student investigated how the acceleration of a trolley is affected by the force acting on the trolley. Figure 16 shows some of the equipment used.

Describe a method the student could use. Your answer should include any extra equipment needed.

Table 2 shows one set of results for a similar investigation.

Which of Newton’s laws predicts that the acceleration of the trolley is proportional to the resultant force on the trolley? Tick (✓) one box.

Determine the acceleration of the trolley when the resultant force is 3.6 N. Use Table 2.

Use the Physics Equations Sheet to answer questions 07.4 and 07.5.

Write down the equation that links acceleration (a), mass (m) and resultant force (F).

A resultant force of 0.42 N acts on a different trolley.

Calculate the mass of the trolley.

A student investigated how the acceleration of a trolley is affected by the force acting on the trolley. Figure 3 shows some of the equipment used.

Describe a method the student could use. Your answer should include any extra equipment needed.

Table 1 shows one set of results for a similar investigation.

Which of Newton’s laws predicts that the acceleration of the trolley is proportional to the resultant force on the trolley? Tick (✓) one box.

Determine the acceleration of the trolley when the resultant force is 3.6 N. Use Table 1.

Use the Physics Equations Sheet to answer questions 02.4 and 02.5.

Write down the equation that links acceleration (a), mass (m) and resultant force (F).

A resultant force of 0.42 N acts on a different trolley.

Calculate the mass of the trolley.

A teacher demonstrated the motor effect. Figure 5 shows the equipment used. The equipment includes a permanent magnet.

The copper rod remains stationary while the switch is open. Complete the sentence. The tendency for an object to remain stationary is

When the switch is closed the copper rod accelerates.

In which direction will the copper rod accelerate? Tick (✓) one box.

Explain one way the teacher could increase the acceleration of the copper rod.

The magnet used in the demonstration was a permanent magnet. Figure 6 shows an iron bar and a permanent magnet.

Describe how the permanent magnet could be used to test if the iron bar is also a permanent magnet.

Figure 7 shows a magnetic compass used by walkers.

Explain how a magnetic compass provides evidence that the Earth has a magnetic field.

Figure 4 shows an apple hanging from a tree. The X marks the centre of mass of the apple.

Draw an arrow on Figure 4 to represent the weight of the apple.

The apple has a mass of 0.150 kg gravitational field strength = 9.8 N/kg Calculate the weight of the apple. Use the equation: weight = mass × gravitational field strength

The apple in Figure 4 is stationary. Why is the apple stationary? Tick (✓) one box.

When the apple is ripe it falls from the tree and accelerates towards the ground.

Why does the apple accelerate? Tick (✓) one box.

The acceleration of the apple is 9.8 m/s² The velocity of the apple changes from 0 to 4.9 m/s Calculate the time taken for the apple to fall to the ground. Use the equation:

The distance a car travels during the driver’s reaction time is called the thinking distance.

Figure 9 shows how thinking distance depends on speed for a car.

Determine the driver’s reaction time. Use the Physics Equations Sheet.

Figure 10 shows how the velocity of a car changes during braking.

Determine the braking distance of the car.

Explain how the gradient of the line on Figure 10 shows that the resultant force on the car was not constant.

Professional rugby players wear a tracking device that measures their velocity and acceleration.

Figure 9 shows a player wearing a tracking device.

The player is tackling another player who is running with the ball.

Velocity and acceleration are both vector quantities.

What is a vector quantity?

Tick (✓) one box.

Which of the following is a vector quantity?

Tick (✓) one box.

Figure 10 shows a velocity–time graph for the player running with the ball.

Determine the acceleration of the player between 0 and 1.6 s.

Describe the motion of the player between 3.4 s and 3.6 s.

The force exerted on the player when she is tackled causes her to accelerate.

Write down the equation which links acceleration (a), mass (m) and resultant force (F).

The player accelerates at 25 m/s² when a resultant force of 1800 N acts on her.

Calculate the mass of the player.

The tracking device sends data to a computer during the game.

Suggest one advantage of the data being sent during the game.

Professional rugby players wear a tracking device that measures their velocity and acceleration. Figure 2 shows a player wearing a tracking device. The player is tackling another player who is running with the ball.

Velocity and acceleration are both vector quantities. What is a vector quantity? Tick (✓) one box.

Which of the following is a vector quantity? Tick (✓) one box.

Figure 3 shows a velocity–time graph for the player running with the ball.

Determine the acceleration of the player between 0 and 1.6 s.

Describe the motion of the player between 3.4 s and 3.6 s.

The force exerted on the player when she is tackled causes her to accelerate.

Write down the equation which links acceleration (a), mass (m) and resultant force (F).

The player accelerates at 25 m/s² when a resultant force of 1800 N acts on her. Calculate the mass of the player.

The tracking device sends data to a computer during the game. Suggest one advantage of the data being sent during the game.

Scientists are developing a hypersonic aeroplane that will travel much faster than normal aeroplanes.

An aeroplane accelerates from a low speed to a high speed with the engines at maximum power. Explain why the acceleration is not constant.

The hypersonic aeroplane will have jet engines and a rocket engine. The speed of aeroplanes can be measured on a uniform scale called the Mach scale. Mach 1 = 330 m/s The jet engines will accelerate the aeroplane to Mach 5.5. The rocket engine will accelerate the aeroplane from Mach 5.5 to Mach 25.5 in 300 s. The average resultant force on the aeroplane when the rocket engine is used will be 630 000 N. Calculate the mass of the hypersonic aeroplane. Give your answer to 2 significant figures.

Figure 5 shows a distance-time graph for 50 seconds of a bicycle ride.

The gradient of the distance-time graph gives the speed of the bicycle. Determine the speed of the bicycle.

Which force acting on the moving bicycle is a non-contact force? Tick (✓) one box.

The bicycle travels a distance of 250 m The bicycle exerts a constant horizontal force of 30 N on the ground. Calculate the work done. Use the equation: work done = force × distance Choose the unit from the box.

The bicycle travels at a constant speed. Complete the sentences. Choose answers from the box.

A student investigated how the height of a ramp affects the acceleration of a trolley down the ramp. Figure 11 shows some of the equipment used.

Plan an investigation to determine how the height of the ramp affects the acceleration of the trolley.

Table 2 shows the results.

The first two results have been plotted on Figure 12.

Complete Figure 12. You should:

• label the axes

• plot the remaining results from Table 2

• draw a line of best fit.

Write down the equation that links acceleration (a), mass (m) and resultant force (F).

When the resultant force on the trolley was 0.63 N the acceleration of the trolley

Calculate the mass of the trolley.

A student investigated how the height of a ramp affects the acceleration of a trolley down the ramp. Figure 3 shows some of the equipment used.

Plan an investigation to determine how the height of the ramp affects the acceleration of the trolley.

Table 1 shows the results.

The first two results have been plotted on Figure 4.

Complete Figure 4. You should:

• label the axes

• plot the remaining results from Table 1

• draw a line of best fit.

Write down the equation that links acceleration (a), mass (m) and resultant force (F).

When the resultant force on the trolley was 0.63 N the acceleration of the trolley

Calculate the mass of the trolley.

Figure 3 shows a gymnast on a piece of gymnastic equipment.

The equipment consists of two bars at different heights.

The gymnast exerts a downward force on the bar.

What is the size of the upward force acting on the gymnast from the bar?

Tick (✓) one box.

Why is the weight of the gymnast represented by an arrow?

Tick (✓) one box.

Figure 3 shows the weight of the gymnast acting from a point.

What name is given to this point?

Tick (✓) one box.

The gymnast has a mass of 45 kg

gravitational field strength = 9.8 N/kg

Calculate the weight of the gymnast.

Use the equation:

weight = mass × gravitational field strength

The gymnast swings from one bar to the other bar several times.

Describe how the gravitational potential energy store and the kinetic energy store of the gymnast change as she moves between the bars.

Falling on the crash mat reduces the average deceleration of the gymnast compared with falling on a hard surface.

Explain why reducing the deceleration is important to the gymnast.

Figure 4 shows two children playing table tennis.

The boy hits the ball from one end of the table.

Why does the velocity of the ball change when the boy hits it?

Tick (✓) one box.

The ball has an average speed of 11 m/s

The ball takes 0.25 s to travel the same distance as the length of the table.

Calculate the length of the table.

Use the equation:

distance travelled = speed × time

A table tennis ball should only be used if it bounces to at least 75% of the height it was dropped from.

A manufacturer tested a table tennis ball.

Table 1 shows the results.

Determine whether the ball can be used.

Use the data from Table 1.

Figure 5 shows two table tennis balls.

The balls are different sizes but have the same mass.

Both balls were dropped onto the table from the same height.

After they were dropped, the resultant force on the smaller ball was greater than the resultant force on the larger ball.

Explain why.

Figure 9 shows a free body diagram for an aeroplane flying at a constant speed and at a constant height.

The speed of the aeroplane is much greater than the speed at which the aeroplane lands.

Explain how the forces need to change so the aeroplane can land.

The aeroplane lands at a speed of 80 m/s

After landing, the aeroplane takes 28 s to decelerate to a speed of 10 m/s

The mean resultant force on the aeroplane as it decelerates is 750 000 N

Calculate the mass of the aeroplane.

Figure 4 shows a man doing two stages of a pull up. In both diagrams the man is stationary.

Complete the sentence.

Choose the answer from the box.

upwards force of the bar on the man.

The man has a mass of 85 kg

Gravitational field strength = 9.8 N/kg

Calculate the weight of the man.

Use the equation:

weight = mass × gravitational field strength

The man raises his body a vertical distance of 0.63 m to go from stage 1 to stage 2

Calculate the work done by the man.

Use your answer to question 03.2

Use the equation:

work done = force × distance

The man was not moving at stage 2 How much work is done by the man at stage 2?

A woman uses the bar to do a pull up.

The woman has a mass of 62 kg

Calculate the resultant force on the woman.

Use the equation:

force = mass × acceleration

A student investigated acceleration using gliders, an air track and light gates.

The air track reduces friction between the glider and the track to zero.

Figure 11 shows the apparatus.

The glider was released from rest and moved along the track.

The mass holder hit the ground before the card passed through the second light gate.

Which two statements describe the effect this would have on the glider?

Tick two boxes.

The mass holder should not hit the ground before the card passes through the second light gate.

Suggest one way that the student could stop this happening.

The student increased the resultant force acting on the glider by adding more masses to the mass holder.

She calculated the acceleration of the glider for each resultant force.

Each test was done three times.

Table 2 shows the results.

The student made two mistakes in the mean acceleration column.

Identify the mistakes the student made.

Suggest how each mistake can be corrected.

Write a conclusion for this investigation.

Use the data in Table 2

The student used a constant resultant force to accelerate the glider.

The student changed the mass of the glider and calculated the new acceleration.

She repeated this for different masses of the glider, keeping the resultant force constant.

The results are shown in Table 3

Plot the results on Figure 12

Draw a line of best fit.

Describe the relationship between mass and acceleration.

A student investigated acceleration using gliders, an air track and light gates. The air track reduces friction between the glider and the track to zero. Figure 1 shows the apparatus.

The glider was released from rest and moved along the track. The mass holder hit the ground before the card passed through the second light gate.

Which two statements describe the effect this would have on the glider? Tick two boxes.

The mass holder should not hit the ground before the card passes through the second light gate. Suggest one way that the student could stop this happening.

The student increased the resultant force acting on the glider by adding more masses to the mass holder. She calculated the acceleration of the glider for each resultant force. Each test was done three times. Table 1 shows the results.

The student made two mistakes in the mean acceleration column. Identify the mistakes the student made. Suggest how each mistake can be corrected.

Write a conclusion for this investigation. Use the data in Table 1

The student used a constant resultant force to accelerate the glider. The student changed the mass of the glider and calculated the new acceleration. She repeated this for different masses of the glider, keeping the resultant force constant. The results are shown in Table 2

Plot the results on Figure 2 Draw a line of best fit.

Describe the relationship between mass and acceleration.

Figure 10 shows the horizontal forces acting on a man swimming in the sea.

Describe the movement of the man when the resultant horizontal force is 0 N

The man increases Force A. Explain what happens to Force B and to the movement of the man.

A boat moves through the sea. There is a 3000 N force to the west on the boat. There is a 1000 N force to the south on the boat. Determine the magnitude and direction of the resultant force on the boat. Draw a vector diagram of these forces to scale on Figure 11

The force to the south on the boat increases. What effect does this have on the resultant force on the boat?