A puck with a mass m₁ = 50.0 g moving at 1.00 m/s approaches a stationary puck with a mass m₂ = 100 g on an air table and they undergo a two-dimensional elastic collision. After the collision, both pucks have identical speeds, but travel in different directions. What is the angle between the original and final paths of m₁? A) 30.0° B) 60.0° C) 90.0° D) 120° E) 150°

Question

Quizplus · Accepted Answer

Since the collision is elastic and total momentum is conserved, we know the final velocity vectors of the two pucks must be at 90° to each other. This is because for the final momenta to cancel out horizontally and vertically, the two velocities must be equal in magnitude and at right angles. Since the original velocity vector of the smaller puck and one of the final velocity vectors make up a right triangle, the angle between them is 90°.

A Puck with a Mass M1 = 50

A Puck with a Mass M₁ = 50