A student investigates the stretching of a spring using a vertical metre rule, a clamp stand, and various weights. The initial unstretched length of the spring is l0l_0l0. Under different loads LLL, the student records the total length l l\,l of the coiled part of the spring.
The results obtained are shown in the table below:
L / N0.01.02.03.04.05.0l / mm25456585105125 \begin{array}{|c|c|c|c|c|c|c|} \hline L \text{ / N} & 0.0 & 1.0 & 2.0 & 3.0 & 4.0 & 5.0 \\ \hline l \text{ / mm} & 25 & 45 & 65 & 85 & 105 & 125 \\ \hline \end{array} L / Nl / mm0.0251.0452.0653.0854.01055.0125Describe one precaution that the student should take to obtain reliable and accurate readings of the spring length.
State whether the results support the suggestion that the total length l l\,l of the spring is directly proportional to the load LLL. Justify your answer.
Calculate the load L L\,L that would stretch the spring to a total length equal to twice the initial unstretched length l0l_0l0. Show your working.
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.