PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two identical, uniform hockey pucks each of mass m and radius R=0.050m slide without friction on a horizontal ice rink. The pucks approach one another along the same straight line with equal speeds v0=3.0ms−1 and collide head-on.
Throughout the motion you may neglect any rotation of the pucks prior to contact.
(1) Treating each puck as a point mass located at its center, calculate the time t0 from the instant the separation between their centers is 0.80m until the instant the pucks’ centers coincide.
(2) State the actual center-to-center separation of the pucks at the moment when their outer rims first touch.
(3) Determine the actual time tcontact from the initial separation 0.80m until the pucks first make physical contact.
(4) Compute the percentage difference between tcontact and t0. Discuss whether the point-mass approximation is justified for predicting collision timing in this situation.