Forces & Elasticity (Edexcel GCSE Physics)

Figure 14 shows a spring standing on a table.

Figure 14a  Figure 14b Figure 14c

 Weights are added to the spring as shown in Figures 14b and 14c.

(i) Estimate the original length of the spring as shown in Figure 14a.

original length = .......................................... mm[1]

(ii) Describe how the reduction in the length of the spring when weights are added can be determined.

[2]

(iii) State two ways that the experimental procedure could be improved.

[2]

(iv) Give one reason why the reduction in length eventually reaches a limit as more weights are added.

[1]

A different spring is extended.

A force of 0.50 N gives an extension of 13 mm.

Calculate the spring constant k in N/m.

spring constant k = .................................... N/m

Another spring is extended.

The work done to extend the spring is 0.14 J.

The spring constant of the spring is 175 N/m.

Calculate the extension of the spring.

Use an equation selected from the list of equations at the end of this paper.

extension of spring = .................................. m

Figure 10 shows a toy used to launch a ball.

Figure 10

One end of the spring is fixed to the handle. The other end of the spring is fixed to the support.

A child pulls the handle, stretching the spring.

Figure 11 shows the toy with the spring stretched.

Figure 11

(i) Which of these shows the forces acting on the handle when the child keeps the spring stretched?

Ignore the force due to gravity.

[1]

(ii) In Figure 11, the extension of the spring is 0.070 m.

The spring constant (k) is 20 N/m.

Calculate the force used to extend the spring. Use the equation

force = k × extension

force = ................................ N[2]

The child pulls the handle until the pad is against the support as shown in Figure 12.

Figure 12

(i) The extension of the spring is 0.09 m.

The spring constant (k) is 20 N/m.

Calculate the work done in extending the spring by 0.09 m.

Use the equation

work done = 1⁄2 × k ×(extension)²

work done = ............................................ J[2]

(ii) The child lets go of the handle.

The ball starts to move.

The spring returns to its original length.

Describe the energy transfer that takes place when the ball starts to move.

[2]

(iii) The child can only stretch the spring until the pad is pressing against the support.

Explain how the design of the toy prevents the spring from becoming damaged.

[2]

Figure 9 shows a 10 N weight hanging from a spring.

Figure 9

One of the forces acting to stretch the spring is shown in Figure 9.

Complete Figure 9 by adding an arrow to show the other force acting to stretch the spring.

A weight of 4.0 N is used to extend a spring.                    

The extension of the spring is 0.06 m.                           

(i) Calculate the spring constant, k, of the spring.

Use the equation

F = k × x

spring constant = ..................................... N/m [3]

(ii) State what measurements should be made to determine the extension of the spring produced by the 4.0 N weight.

[2]

Another spring has a spring constant of 250 N/m.

Calculate the work done in stretching the spring by 0.30 m.

State the unit.

Use the equation

work done in stretching the spring = ............. unit ..........

Figure 1 shows how the extension of a spring varies when different loads are hung from it.

Figure 1

Force, extension and temperature are variables for this investigation.

Identify which variable is:

(i) Dependent variable

[1]

(ii) Independent variable

[1]

(iii) A control variable

[1]

Write a plan for an investigation into how the extension varies with load.

The plan should include details of how to make accurate measurements.

You may add to the diagram to help your answer.

The spring obeys Hooke’s law. 

Label the axes, and draw a graph on the axes to show Hooke’s law relationship.

Explain what is meant by the term elastic behaviour.

A student wishes to investigates the extension of a spring when masses are added.

List three items of equipment that would be required.

Describe how the student can determine the extension of the spring.

The student plots a graph of load against extension, as shown in Figure 1.

Figure 1

(i) Determine the extension produced by a load of 7.5 N.

extension = ................................ cm[1] 

(ii) Determine the load that would produce an extension of 10.0 cm. 

load = ..................................... N[2]

(i) State which feature of the graph gives the spring constant.

[1]

(ii) Determine the spring constant, k, of the spring.

spring constant = .................................... N / kg[2]

The diagrams show springs hanging on a nail.

• In Diagram 1 there is no weight on the spring.

• Diagram 2 shows the spring after a weight is added.

• Diagram 3 shows the spring after the weight has been pulled down slightly, where it is currently held.

Figure 1

Describe the energy change that takes place until the spring is stationary again.

Higher Tier Only

Shock absorbers with springs are used on motorbikes. They reduce the bounce of an uneven road. It consists of magnets which slide inside a coil when the car goes over a bump, as shown in Figure 2.

Figure 2

The system is connected to an external circuit.

Figure 3 shows the bumps on the surface of two roads, L and M. 

Figure 3

Assuming the car travels at the same speed on each road, compare and contrast the effect on both roads on the external circuit.

A digital calliper is an apparatus used to measure the length of objects within 0.01 mm. It can be used to measure the length of a spring as shown in Figure 1.

Figure 1

A student takes 6 readings of the unstretched length of the spring.

i) Calculate the average length of the unstretched spring.

[2]

ii) Explain why this value will not be very accurate.

[1]

The student investigates the stretching of a spring with the equipment shown in Figure 2.

Figure 2

The student investigates the extension of the spring using seven different weights.

The results are shown in Figure 3.

Figure 3

Draw a graph for the readings, using the grid shown.

The student extends the investigation by finding information about the stretching of wires.

The student finds the graph shown in Figure 4 for the stretching of a wire.

Figure 4

Describe the stretching of the wire after an extension of 5 mm.

A student used the spring, a set of weights and a ruler to investigate how the extension of the spring depended on the weight hanging from the spring.

Figure 1 shows that the ruler is in a tilted position and not upright as it should be.

Figure 1

Explain how leaving the ruler tilted affects the weight and extension data recorded by the student.

The metre ruler is corrected to be upright again. Figure 2 shows the spring before and after some weight is added.

Figure 2

The energy transferred in stretching the spring is 0.15 J.

Calculate the weight added to the spring to produce this extension.

The student completes the experiment by adding all the masses provided and measuring the extension of the spring.

Explain how the student could test if the spring has gone through inelastic distortion.