Hockey puck ?B? rests on a smooth ice surface and is struck by a second puck ?A?, which has the same mass. Puck ?A? is initially traveling at 15.0 m/s and is deflected 25.0° from its initial direction. Assume that the collision is perfectly elastic. Find the final speed of each puck and the direction of ?B?’s velocity after the collision.

Solution 99P Step 1 of 6: Step 2 of 6: There is no external force so p and p are conserved x y 0 0 0 0 0 The collision is elastic, so 25 + B 90 , = 90B 25 = 65 Step 3 of 6: p is conserved so x mA A1x + m B B1x = m A A2x + m B B2x m = m , so v = v cos25 + v cos 65 0 ....(1) A B A1 A2 B2