Forces & elasticity

Figure 12 shows an Olympic gymnast performing a floor routine.

The floor contains springs.

When the gymnast lands on the floor, a force compresses the springs in the floor.

When a spring is compressed, the elastic potential energy of the spring increases.

Explain why compressing the springs in the floor helps the gymnast to jump higher.

Use ideas about energy in your answer.

When the gymnast lands on the floor, one of the springs compresses by 1.2 cm.

spring constant = 8500 N/m

Calculate the elastic potential energy stored in the spring.

Use the Physics Equations Sheet.

Give the unit.

A student investigated a spring with a different spring constant.

When masses are placed on the spring it compresses.

The student measured the compression of the spring for different masses.

Figure 13 shows some of the equipment used.

Describe how the compression of the spring could be determined.

Explain why the investigation should be done on the laboratory floor rather than on a table.

Figure 14 shows the results.

The spring constant is the gradient of the line of best fit shown on Figure 14.

Determine the value Δ y on Figure 14.

Determine the value Δ x on Figure 14.

Determine the spring constant of the spring.

Use your answers to Question 07.5 and Question 07.6.

Give your answer to 3 significant figures.

Figure 2 shows an Olympic gymnast performing a floor routine.

The floor contains springs.

When the gymnast lands on the floor, a force compresses the springs in the floor.

When a spring is compressed, the elastic potential energy of the spring increases.

Explain why compressing the springs in the floor helps the gymnast to jump higher.

Use ideas about energy in your answer.

When the gymnast lands on the floor, one of the springs compresses by 1.2 cm.

spring constant = 8500 N/m

Calculate the elastic potential energy stored in the spring.

Use the Physics Equations Sheet.

Give the unit.

A student investigated a spring with a different spring constant.

When masses are placed on the spring it compresses.

The student measured the compression of the spring for different masses.

Figure 3 shows some of the equipment used.

Describe how the compression of the spring could be determined.

Explain why the investigation should be done on the laboratory floor rather than on a table.

Figure 4 shows the results.

The spring constant is the gradient of the line of best fit shown on Figure 4.

Determine the value Δ y on Figure 4.

Determine the value Δ x on Figure 4.

Determine the spring constant of the spring.

Use your answers to Question 02.5 and Question 02.6.

Give your answer to 3 significant figures.

Figure 1 shows a garden chair hanging from a spring.

The weight of the person causes the spring to extend.

Why does the weight of the person cause the spring to extend? Tick (✓) one box.

Complete the sentence. Choose the answer from the box.

The weight of the person in Figure 1 is force.

The weight of the person causes an extension in the spring of 0.070 m.

The spring constant of the spring is 12 000 N/m.

Calculate the weight of the person. Use the equation: weight = spring constant × extension

Calculate the elastic potential energy stored in the extended spring. Use the equation: elastic potential energy = 0.5 × spring constant × (extension)²

If there is more than one person on the chair, the spring could become inelastically deformed. What is meant by ‘inelastically deformed’? Tick (✓) one box.

The manufacturer of the chair investigated the extension of a new spring.

Figure 2 shows slotted masses hanging from the spring. The weight of the masses extends the spring.

Which length in Figure 2 represents the extension of the spring? Tick (✓) one box.

Which graph shows that the extension of the spring is directly proportional to the force applied to the spring? Tick (✓) one box.

Table 1 shows the results of the manufacturer’s investigation.

Suggest two improvements to the investigation.

Figure 8 shows a garden chair hanging from a spring.

Which of the following describes the relationship between the weight (W) acting on the spring and the extension (e) of the spring? Tick (✓) one box.

The person in Figure 8 has a weight of 750 N. The person’s weight causes the spring to extend by 60 mm. Calculate the spring constant of the spring. Use the Physics Equations Sheet.

The manufacturer of the chair tests a new spring to see if it is suitable to hang

the chair. The spring can store a maximum of 1800 J of elastic potential energy before it becomes inelastically deformed.

Describe what is meant by ‘inelastically deformed’.

Calculate the maximum extension of the spring before the spring becomes inelastically deformed. spring constant = 225 N/m Use the Physics Equations Sheet.

Evaluate the suitability of the new spring to hang the chair. maximum elastic potential energy = 1800 J spring constant = 225 N/m weight of person = 750 N distance between the bottom of the chair and the ground = 30 cm Include a calculation in your answer. Use the Physics Equations Sheet.

Figure 8 shows a stretched spring.

The spring is elastically deformed.

What is meant by ‘elastically deformed’?

Tick (✓) one box.

Describe a method to determine the extension of the spring.

The extension of the spring is 80 mm.

spring constant = 40 N/m

Calculate the elastic potential energy of the spring.

Use the Physics Equations Sheet.

Write down the equation which links extension (e), force (F) and spring constant (k).

A force of 300 N acts on a different spring.

The force causes the spring to extend by 0.40 m.

Calculate the spring constant of the spring.

Figure 1 shows a stretched spring. The spring is elastically deformed.

What is meant by ‘elastically deformed’? Tick (✓) one box.

Describe a method to determine the extension of the spring.

The extension of the spring is 80 mm. spring constant = 40 N/m Calculate the elastic potential energy of the spring. Use the Physics Equations Sheet.

Write down the equation which links extension (e), force (F) and spring constant (k).

A force of 300 N acts on a different spring. The force causes the spring to extend by 0.40 m. Calculate the spring constant of the spring.

Figure 3 shows a computer keyboard. There is a spring under each key.

Why do the keys have springs under them? Tick (✓) one box.

Why does every spring used in the keyboard have the same spring constant? Tick (✓) one box.

Figure 4 shows one of the keys and its spring.

What happens to the length of the spring when the key is pressed?

How far must the key move before it touches the switch? Tick (✓) one box.

If a key is not pressed with enough force, no signal is sent to the computer. Explain why.

The spring in Figure 4 has a spring constant of 200 N/m Calculate the force on the spring when the key moves a distance of 0.0040 m Use the equation: force = spring constant × compression

Suggest two ways the spring in the key in Figure 4 could be changed so that the switch can be closed more quickly.

Figure 5 shows a computer keyboard. There is a spring under each key.

The springs behave elastically when a force is applied. What is meant by elastic behaviour? Tick (✓) one box.

Suggest two properties that should be the same for each spring.

Figure 6 shows one of the keys and its spring.

The key must be pressed with a minimum force of 0.80 N before the key touches the switch. Calculate the spring constant of the spring in Figure 6.

Figure 7 shows a spring that has been hung from a support. The spring is stationary and has been stretched beyond its limit of proportionality.

Which two statements are true for the spring in Figure 7 ?

Tick (✓) two boxes.

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 6 shows a man using a resistance band when exercising.

The resistance band behaves elastically.

What happens to the store of elastic potential energy of the resistance band when the band is stretched?

Explain what happens to the resistance band as it is released.

Figure 7 shows how the extension of the resistance band changes as the force applied changes.

Describe the trend shown in the graph.

Figure 8 shows a chest expander.

Sketch a graph on Figure 9 to show how the extension of a spring in the chest expander changes as the force applied changes.

When a force is applied to a spring, the spring extends by 7.5 cm

Write down the equation that links extension, force and spring constant.

Calculate the force applied to the spring.

The spring has a spring constant of 1 600 N/m

Use your equation from question 05.5

Figure 6 shows four newtonmeters. Each newtonmeter contains a spring.

Which newtonmeter has the spring with the greatest spring constant? Give a reason for your answer.

The newtonmeter in Figure 7 will give an error when used to make a measurement.

Name the type of error. Describe how this error can be corrected.

A student hangs a weight on a newtonmeter. The energy now stored in the spring in the newtonmeter is 4.5 × 10^–2 J The student then increases the weight on the newtonmeter by 2.0 N Calculate the total extension of the spring. Spring constant = 400 N/m