An experiment is carried out to investigate how a vertical spring stretches under different loads.
The unstretched length of the spring is measured first. Describe two precautions that should be taken when measuring the length of the stationary spring with a metre rule to ensure an accurate reading.
A student measures the length l0l_0l0 of the spring without any load:
l0=3.5 cm l_0 = 3.5 \text{ cm} l0=3.5 cmVarious loads LLL are hung on the spring. The stretched length lll of the spring for each load is recorded in the table below.
| L / NL \text{ / N}L / N | l / cml \text{ / cm}l / cm | e / cme \text{ / cm}e / cm |
|---|---|---|
| 1.5 | 8.3 | |
| 3.0 | 13.1 | |
| 4.5 | 17.9 |
Calculate, and write down, the extension eee of the spring for each load LLL. Use the equation e=l−l0e = l - l_0e=l−l0.
The loads are removed and an object Y\text{Y}Y is suspended from the spring.
The student measures the stretched length lYl_{\text{Y}}lY of the spring with object Y\text{Y}Y attached to be 11.5 cm11.5 \text{ cm}11.5 cm. Calculate the extension eYe_{\text{Y}}eY.
Estimate the weight WYW_{\text{Y}}WY of object Y\text{Y}Y. Explain how you obtained your answer using the data.
Another student measures the weight of a different load using a similar method. He records the weight as 2.1875 N2.1875 \text{ N}2.1875 N. Explain why this is not a suitable number of significant figures for this experiment.
A student suggests that the extension eee is directly proportional to the load LLL. State whether the results in the table support this suggestion, and justify your statement using values from the results.
The student wishes to plot a graph of LLL against eee to test if the two quantities are directly proportional. State two features of the graph line that would show direct proportionality.
245 exam-style questions on CIE IGCSE Physics 1.5 Forces, covering 1.5.1a Forces, resultant force and motion, 1.5.1b Load–extension graphs and the spring constant, 1.5.1c Friction and drag, 1.5.1d Force, mass and acceleration, 1.5.1e Motion in a circular path, 1.5.2a Moment of a force, 1.5.2b Principle of moments and equilibrium, and 1.5.3 Centre of gravity and stability. Each one has a worked solution and a mark scheme showing where the marks go.