A physics research team is investigating collisions between two identical…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A physics research team is investigating collisions between two identical low-friction pucks on a horizontal air table. The pucks are equipped with tiny reflectors so that an overhead motion-tracking camera can record their positions as a function of time both before and after the pucks collide.
The investigators want to know what kind of collision occurs under different experimental conditions (polished steel pucks, pucks with rubber bumpers, pucks wrapped in soft clay, etc.). The camera system can provide the speed of each puck at any instant, but it cannot directly measure forces or energies.
Assume friction with the air table surface and air resistance are negligible during the short collision interval.
(a) Describe the specific physical quantities you would extract from the motion-tracking data in order to decide whether a particular collision is elastic, inelastic, or perfectly inelastic.
(b) Explain, in a clear sequence of reasoning, how you would use the measured quantities from part (a) to reach a conclusion about the collision type.
(c) Suppose the total kinetic energy of the system is found to decrease by 8% between the instants just before and just after a collision in which the pucks do not stick together. State how you would classify this collision and justify your choice in one or two well-organized sentences.