Question

A 0.30 kg puck, initially at rest on a frictionless horizontal surface, is struck by a 0.20 kg puck that is initially moving along the x axis with a velocity of 2.8 m/s. After the collision, the 0.20 kg puck has a speed of 0.5 m/s at an angle of θ = 53° to the positive x axis.

(a) Determine the velocity of the 0.30 kg puck after the collision.
(b) Find the fraction of kinetic energy lost in the collision.

Answer 1

(a) Use the same method i suggested here:
http://www.jiskha.com/display.cgi?id=1319256261

Part (b) will be easy once you do part (a).
Just compare initial kinetic energy with final total kinetic energy of both pucks.