1.1. 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]

1.2. 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.

1.3. 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.