Forces & Energy Changes (AQA GCSE Combined Science: Synergy: Physical Sciences): Exam Questions

The 0.025 kg mass dropped through a height of 0.60 m.

Calculate the change in gravitational potential energy of this mass.

gravitational field strength = 9.8 N/kg

Use the equation:

$\text{gravitational potential energy}=\text{mass}\times \text{gravitational field strength}\times \text{height}$

The braking distance of a vehicle depends on the mass of the vehicle.

Use the Physics Equations Sheet to answer questions 1.2 and 1.3.

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

Calculate the mass of a vehicle with a weight of 14 700 N.

gravitational field strength = 9.8 N/kg

A student investigated how the acceleration of a glider varied with the mass of the glider.

The force causing the acceleration was constant.

Figure 13 shows the equipment used.

The air blower allows the glider to move along the air-track with very little friction.

Figure 13

This is the method used.

1. Line up the front of the glider with the marker.

2. Release the glider.

3. Record the velocity as the glider passes through the light gate.

4. Calculate the acceleration of the glider.

5. Repeat steps 1 to 4 using gliders of different mass.

The mass on the mass holder was 25 g.

The change in gravitational potential energy of the mass was 0.147 J.

gravitational field strength = 9.8 N/kg

Calculate the change in height of the mass.

Use the Physics Equations Sheet.

Figure 14 shows the results.

The student concluded:

'The acceleration of the glider is inversely proportional to the mass of the glider.'

Explain why the student was correct.

Use data from Figure 14 in your answer.

A different student did the investigation using a trolley instead of an air blower and glider.

Figure 15 shows the equipment.

Figure 15

Give one way that the student could make the trolley roll more easily along the bench.

Figure 16 shows a student using a catapult to launch a small stone.

The catapult contains a spring.

Figure 16

What is the relationship between the extension of a spring and the force applied to the spring?

The extension of the spring is 20 cm.

The elastic potential energy stored by the spring is 1.16 J.

Calculate the spring constant of the spring.

Use the Physics Equations Sheet.

The student used the catapult to launch stone A and then stone B.

The spring had the same extension for each stone.

Stone B has a mass 4 times greater than stone A.

Explain the difference in the speed of stone A and the speed of stone B as they are launched from the catapult.

Your answer should include a calculation.

Use the Physics Equations Sheet.

Some catapults use a rubber band instead of a spring.

A student investigated how the extension of a rubber band varied with the force on the rubber band.

Figure 17 shows the results.

Figure 17

Explain why additional readings would allow the student to make a conclusion more easily.

Do not refer to repeat readings or calculating a mean.

To make a fair comparison between the braking distance of the two cars, the mass of each car was the same.

Calculate the weight of a car.

mass = 850 kg

gravitational field strength = 9.8 N/kg

Use the equation:

$\text{weight}=\text{mass}\times \text{gravitational field strength}$

Choose the unit from the box.

Weight = ______________ Unit _____________

Figure 1 shows a floating hot air balloon attached to the ground by a rope. The hot air balloon is stationary.

The wind is exerting a force on the hot air balloon in Figure 1.

Which arrow shows the direction of the force of the wind in Figure 1?

Tick (✓) one box.

Which force causes the hot air balloon to float?

Tick (✓) one box.

The hot air balloon in Figure 1 is stationary.

What is the resultant force on the balloon?

Tick (✓) one box.

The mass of the hot air balloon is 350 kg.

Calculate the weight of the hot air balloon.

gravitational field strength = 9.8 N/kg

Use the equation:

weight = mass × gravitational field strength

The hot air balloon exerts a force of 200 N on the rope.

The force causes the rope to stretch by 1.60 m.

The rope behaves like a spring.

Calculate the spring constant of the rope.

Use the equation:

$\text{spring constant}=\frac{\text{force}}{\text{extension}}$

Choose the unit from the box.

This question is about forces.

Force is a vector quantity.

Which is a correct statement about a vector quantity?

Tick (✓) one box.

A newtonmeter measures the weight of an object.

What is the weight of the object in Figure 1?

Weight = N

An object has a weight of 6.4 N.

Calculate the mass of the object.

Use the equation:

$\text{mass}=\frac{\text{weight}}{\text{gravitational field strength }\left(g\right)}$

gravitational field strength = 9.8 N/kg

Mass = ______________ kg

The mass of a bag of sugar is 1 kg.

• On Earth the weight of this bag of sugar is 10 N.

• On Mars the weight of this bag of sugar is 4 N.

Suggest why the weight of the bag of sugar is different on Earth and on Mars.

Figure 7 shows a rollercoaster.

Figure 7

The rollercoaster car is raised a vertical distance of 35 m to point A by a motor in 45 seconds.

The mass of the rollercoaster is 600 kg.

The motor has a power rating of 8 000 W.

Calculate the percentage efficiency of the motor.

Gravitational field strength = 9.8 N/kg.

Efficiency = ___________ %

The rollercoaster rolls from point A to point B, a drop of 35 m.

Calculate the speed of the rollercoaster at point B.

Assume that the decrease in potential energy store is equal to the increase in kinetic energy store.

Speed at point B = ____________m/s

A student investigated how the extension of a spring varied with the force applied to the spring.

FIGURE 13 shows the equipment used.

This is the method used.

1. Measure the length of the unstretched spring.

2. Hang the spring from the clamp stand.

3. Hang a mass from the spring.

4. Calculate the weight of the mass.

5. Measure the new length of the spring.

6. Calculate the extension of the spring.

7. Repeat steps 3 to 6 for additional masses.

A spring can be elastically or inelastically deformed.

What does 'elastically deformed' mean?

FIGURE 14 shows the results.

The student concluded:

'The extension of the spring is directly proportional to the weight up to a point called the limit of proportionality.'

What was the extension of the spring when the spring reached its limit of proportionality?

Extension =___________ cm

Determine the spring constant of the spring used by the student.

Use the Physics Equations Sheet.

The mass on the spring is stationary after the spring has extended.

The force that the mass exerts on the spring is represented by the vector diagram in FIGURE 15.

Draw an arrow on FIGURE 15 to show the magnitude and direction of the tension in the spring.

Suggest two factors that affect the maximum speed of the person as the sphere reaches the bottom of the hill.

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.

Figure 11 shows a floating hot air balloon attached to the ground by a rope.

Figure 11

The hot air balloon is stationary.

The wind is exerting a force on the hot air balloon in Figure 11.

Which direction is the force of the wind acting?

What is the name of the upwards force on the hot air balloon?

The weight of the hot air balloon is 3.43 kN.

gravitational field strength = 9.8 N/kg

Calculate the mass of the hot air balloon.

Use the Physics Equations Sheet.

The resultant force on the balloon is zero.

What is meant by 'resultant force'?

Figure 12 shows a vector diagram of the force of the rope on the hot air balloon.

Complete the vector diagram to determine the magnitude of the horizontal and vertical components of the force.

Horizontal component = _ N

Vertical component = _ N

A small ball weighs 1.4 N.

gravitational field strength, g = 9.8 N/kg

Calculate the mass of the ball.

Mass = ____________ kg

Forces can be classed as contact or non-contact forces.

Look at Table 4.

Tick (✓) one box for each type of force to say whether it is a contact force or a non-contact force.

Table 4

Force is a vector quantity.

What are two other vector quantities?

Tick (✓) two boxes.

A student does a practical to investigate the relationship between force and extension for a spring.

What could the student do to improve the accuracy of his investigation?

Tick (✓) one box.

The weight on the spring is the force applied to the spring.

The student puts a mass of 25 g on the spring.

Gravitational field strength = 9.8 N/kg

Calculate the weight on the spring.

Use the equation:

$\text{weight}=\text{mass}\times \text{gravitational field strength}$

Weight on spring = N

The student plotted a graph of force applied and extension of the spring.

Figure 6 shows his graph.

Figure 6

What is the relationship between force applied and extension?

Tick (✓) one box.

Use Figure 6 to determine the force needed to give an extension of 4.5 cm.

Force needed = N

A different spring has a spring constant of 13.5 N/m.

Calculate the elastic potential energy stored in the spring when its extension is 12 cm.

Use the correct equation from the Physics equation sheet.

Elastic potential energy = J