Two identical balls collide one was initially at rest. after the collision one of the balls has a velocity of 3 m/s south. the other has a velocity of 4 m/s west. what was the velocity of the ball that was moving before the collision

It's a snowy day and you're pulling a friend along a level road on a sled. you've both been taking physics, so she asks what you think the coefficient of friction between the sled and the snow is. you've been walking at a steady 1.5m/s, and the rope pulls up on the sled at a 32 ∘ angle. you estimate that the mass of the sled, with your friend on it, is 65 kg and that you're pulling with a force of 80 n .