A Hockey Puck with Mass 0

Multiple Choice

A hockey puck with mass 0.250 kg traveling along a line at 2.5 m/s strikes a stationary puck with the same mass.One puck exits the elastic collision in a direction that is 20 degrees away from the line at a speed of 2.35 m/s.What is the speed of the second puck after the collision?

A) 0.85 m/s
B) 2.5 m/s
C) 0.63 m/s
D) 0.73 m/s
E) 0.15 m/s