Al. A puck of mass m, moving at a speed of vi collides with an identical mass stationary puck. After the collision, one puck moves off at an angle of with a speed of vi', and the other puck moves off at an angle p2 with a speed of v2' . a) What are the speeds vi' and v2' if @1 + $2 = 90? Express your answers in terms of v1 and $1. [3 points] b) Is the collision inelastic or (totally) elastic? Support your answer with a calculation. [2 points]