Two hockey pucks with a mass of 0.1 kg slide across the ice and collide. Before the collision puck 1 is going 8 m/s to the east and puck two is Going 7 m/s to the west. After the collision puck one is going 7 m/s to the west. What is the velocity of puck two

Answer 1

letting east by +, we conserve momentum and end up with
0.1(8) + 0.1(-7) = 0.1(-7) + 0.1v
clearly, v = +8