Gce Model Questions Vol1 2025 Physics Question 1

In a laboratory experiment to determine the coefficient of linear expansion (\(\alpha\)) of a steel rod, the following apparatus is used: a steel rod of length \(L_{0}=1.200\,\text{m}\) at \(20^{\circ}\text{C}\) suspended vertically from a fixed support, a set of calibrated weights totalling \(5.0\,\text{kg}\) attached to the lower end, a steel wire scale fixed at the base, and a digital thermometer reading temperature to the nearest \(0.1^{\circ}\text{C}\). The rod is allowed to reach thermal equilibrium at three different ambient temperatures: \(20^{\circ}\text{C}\), \(35^{\circ}\text{C}\) and \(50^{\circ}\text{C}\). The recorded extensions (increase in length) of the rod, measured from the scale, are \(0.0000\,\text{m}\), \(0.0018\,\text{m}\) and \(0.0036\,\text{m}\) respectively. The experiment is repeated with the same rod but with a different set of weights totalling \(2.0\,\text{kg}\), giving extensions of \(0.0000\,\text{m}\), \(0.0012\,\text{m}\) and \(0.0024\,\text{m}\) at the same temperatures.