PHYSICS · Single correct · AP · Physics C: Mechanics · Linear Momentum · Linear Momentum
Problem
Two identical pucks, each of mass m, slide on a horizontal, frictionless ice rink. Puck A travels due east with speed v0 and collides elastically with puck B, which is initially at rest. After the collision, puck A is observed to move at an angle of 60∘ north of east.
Which of the following statements about the motion of puck B immediately after the collision is most consistent with conservation of momentum and kinetic energy?
(a) Puck B moves in a direction that is exactly 90∘ from the direction of puck A after the collision.
(b) Puck B moves 30∘ south of east with speed 21v0.
(c) Puck B moves directly east with speed 23v0.
(d) Puck B remains at rest because the pucks are identical.