Gravity and weight

A student went on a cycling journey that lasted for three days.

The student recorded information about the journey using a cycling app on a mobile phone.

At the start of the journey, the student travelled along a straight road to a road junction.

A map on the cycling app showed the road.

Figure 5 shows the map.

The scale of the map is 1 cm: 20 m

Calculate the distance travelled by the student between the start and the

road junction.

Use Figure 5.

The bicycle had a mass of 15 kg.

gravitational field strength = 9.8 N/kg

Calculate the weight of the bicycle.

Use the equation:

weight = mass × gravitational field strength

Figure 6 shows a velocity–time graph for a downhill part of the journey.

The gradient of the graph represents acceleration.

How does Figure 6 show that the acceleration was constant?

As the student accelerated downhill, the forward force on the student was 250 N.

The work done by the forward force was 4500 J.

Calculate the distance travelled as the student accelerated downhill.

Use the equation:

Most of the roads on the journey were not straight.

Figure 7 shows a map of the route taken for the whole journey.

The line in Figure 7 represents the total distance travelled when the student reached the end of the journey.

How does the total distance travelled compare with the magnitude of the displacement of the student from the start?

Tick () one box.

Why is distance a scalar quantity?

Tick () one box.

Figure 8 shows the distance travelled by the student each day.

Calculate the total distance travelled by the student.

Use Figure 8.

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.

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.

Figure 13 shows an engineer climbing up a ladder.

The distance between each rung on the ladder is 30 cm.

What is 30 cm in metres? Tick (✓) one box.

The engineer has a weight of 710 N. Calculate the work done when climbing up one rung of the ladder. Use your answer to Question 05.1 and the equation: work done = force × distance

The engineer climbs the ladder carrying some equipment. Give the reason why carrying equipment increases the work done by the engineer when climbing the ladder.

The engineer is stationary at the top of the ladder. Which energy stores of the engineer increase due to the engineer climbing the ladder? Tick (✓) two boxes.

Use the Physics Equations Sheet to answer questions 05.5 and 05.6.

Write down the equation that links gravitational field strength (g), mass (m) and weight (W).

The engineer has a weight of 710 N. gravitational field strength = 9.8 N/kg Calculate the mass of the engineer. Give your answer to 2 significant figures.

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:

Forces are either contact forces or non-contact forces.

Which of the following is a non-contact force?

Tick (✓) one box.

Figure 1 shows a person standing on some bathroom scales.

The person exerts a downward force on the scales and the scales exert an upward force on the person.

Which sentence about the forces is true?

Tick (✓) one box.

What is the name of the upward force on the person?

Tick (✓) one box.

The person on the scales has a mass of 55 kg.

gravitational field strength = 9.8 N/kg

Calculate the weight of the person.

Use the equation:

weight = mass × gravitational field strength

The gravitational field strength is not the same at all points on the surface of the Earth.

The gravitational field strength is weakest at the equator.

A person travelled from the UK to the equator.

What happened to the weight of the person?

Tick (✓) one box.

Figure 2 shows the forces acting on a person.

The person is about to jump.

The arrow representing the weight of the person is drawn from point X.

What is the name given to point X ?

Tick (✓) one box.

Determine the size of the resultant force on the person in Figure 2.

Figure 9 shows five different metal samples.

A student placed a magnet close to each metal sample. Describe what happened.

Figure 10 shows a paper clip being attracted to a permanent magnet.

The paper clip in Figure 10 is not a permanent magnet. Explain what would happen if the paper clip was removed and brought close to the south pole of the permanent magnet.

Write down the equation that links gravitational field strength (g), mass (m) and weight (W).

The student added more paperclips to one end of the magnet. The maximum number of paperclips the magnet could hold was 20 Each paper clip had a mass of 1.0 g gravitational field strength = 9.8 N/kg Calculate the maximum force the magnet can exert.

Figure 1 shows five different metal samples.

A student placed a magnet close to each metal sample. Describe what happened.

Figure 2 shows a paper clip being attracted to a permanent magnet.

The paper clip in Figure 2 is not a permanent magnet. Explain what would happen if the paper clip was removed and brought close to the south pole of the permanent magnet.

Write down the equation that links gravitational field strength (g), mass (m) and weight (W).

The student added more paperclips to one end of the magnet. The maximum number of paperclips the magnet could hold was 20 Each paper clip had a mass of 1.0 g gravitational field strength = 9.8 N/kg Calculate the maximum force the magnet can exert.

A student clamped a wire between the poles of a permanent magnet. The student investigated how the force on the wire varied with the current in the wire. Figure 13 shows the equipment used.

The top pan balance was used to determine the force on the wire.

When the switch was closed the reading on the top pan balance increased. Explain why the increased reading showed that there was an upward force on the wire.

Table 3 shows the readings on the top pan balance with the switch open and with the switch closed.

Explain how the values in Table 3 can be used to determine the size of the force on the wire.

The student varied the current in the wire and calculated the force acting on the wire. Figure 14 shows the results.

The length of the wire in the magnetic field was 0.125 m Determine the magnetic flux density.

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 8 shows some springs inside a mattress.

Which proportionality is true when a force is applied to a spring?

Tick (✓) one box.

A mattress contains 1200 identical springs.

A person lies on the mattress and the springs compress.

The mean force on each spring in the mattress is 0.49 N

Calculate the mass of the person.

gravitational field strength = 9.8 N/kg

The mean compression of each spring is 3.5 × 10^–3 m

Calculate the spring constant of each spring in the mattress.

Give the unit.

For a given force, different springs compress by different amounts.

Explain what property of the springs would make the mattress soft.

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