The class is investigating the behaviour of a spring, and then using the spring to determine the weight of an object.
A student hangs various loads LLL on the spring and records the stretched length lll of the spring. The readings are shown in the table below.
| L/NL / \text{N}L/N | l/cml / \text{cm}l/cm |
|---|---|
| 1.0 | 8.1 |
| 2.0 | 11.0 |
| 3.0 | 13.9 |
| 4.0 | 17.2 |
| 5.0 | 19.8 |
Suggest one precaution that you would take when measuring the length of the spring, to ensure a reliable reading.
The student plots a graph of l/cml/\text{cm}l/cm (yyy-axis) against L/NL/\text{N}L/N (xxx-axis). The resulting best-fit straight line has a gradient of 3.0 cm/N3.0\text{ cm/N}3.0 cm/N and passes through the point (2.0,11.0)(2.0, 11.0)(2.0,11.0).
Use this line of best fit to determine: (i) the unstretched length l0l_0l0 of the spring. (ii) the weight WWW of an object that gives a stretched length of l=15.5 cml = 15.5\text{ cm}l=15.5 cm.
A student measures the weight of a different load using this same method. He gives the weight as 2.564 N2.564\text{ N}2.564 N.
Explain why this is not a suitable number of significant figures for this experiment.
183 exam-style questions on CIE IGCSE Physics 1.5.1a Forces, resultant force and motion. Each one has a worked solution and a mark scheme showing where the marks go.