A 70.0-kg ice hockey goalie, originally at rest, catches a 0.150-kg hockey puck slapped at him at a velocity of 35.0 m/ s. Suppose the goalie and the ice puck have an elastic collision and the puck is reflected back in the direction from which it came. What would their final velocities be in this case?

Step-by-step solution In this problem a ice hockey goalie catches a hockey puck which is reflected back in the direction from where it came so, calculate the final velocity if elastic collisions have occurred between them. Step 1 of 7 For an elastic collision, the conservation of momentum is: …… (1) Here is the mass of ice hockey goalie, is the mass of hockey puck, is the velocity of ice hockey goalie, is the velocity of hockey puck, is the velocity after ice hockey goalie, and is the velocity after ice hockey puck. Step 2 of 7 Substitute for , for , for and for . Step 3 of 7 For elastic collision, the kinetic energy also conserved. So, …… (2) Here is the mass of ice hockey goalie, is the mass of hockey puck, is the velocity of ice hockey goalie, is the velocity of hockey puck, is the velocity after ice hockey goalie and is the velocity after ice hockey puck. Step 4 of 7 Substitute for , for , for and for .