A stone of mass is tied to one end of a light inextensible string of length and…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A stone of mass 0.2kg is tied to one end of a light inextensible string of length 1m and whirled in a horizontal circle at constant speed. Assume the only force exerted by the string on the stone is the tension, which is always directed towards the centre of the circle.
(i) For any small segment of motion, what is the angle between the instantaneous displacement of the stone and the tension in the string? Justify your answer.
(ii) Hence, or otherwise, calculate the total work done by the tension in the string on the stone when it completes (a) half a revolution and (b) one full revolution.
(iii) Give a concise explanation, based on your calculations, of why the magnitude of displacement rather than the actual length of the path determines the work done by a force.