Here's a couple of mcs I'm trying to use to study, but they got me stuck and I don't have the answers, much less the explanations. A little help here would be greatly appreciated. 1. A 2kg ball collides with the floor at an angle and rebounds at the same angle and speed as shown above. Which of the following vectors represents the impulse exerted on the ball by the floor? The left and right cancels, leaving only up, so I'm guessing E is the answer? 2-3 22. What is the total kinetic energy of the two-puck system before the collision? (A) √13 J (B) 5.0 J (C) 7.0 J (D) 10 J (E) 11 J For this one I used the kinetic energy equation on the 2 particles and added them, getting 5.0 J so B is the answer. 3. What is the magnitude of the total momentum of the two-puck system after the collision? (A) 1.0 kg.m/s (B) 3.5 kg.m/s (C) 5.0 kg.m/s (D) 7.0 kg.m/s (E) 5.5 √5 kg.m/s I solved for momentum of both, then used pythagorean theorem and got C as the answer 4. As shown above, two students sit at opposite ends of a boat that is initially at rest. The student in the front throws a heavy ball to the student in the back. What is the motion of the boat at the time immediately after the ball is thrown and, later, after the ball is caught? (Assume that air and water friction are negligible.) Immediately After the Throw After the Catch (A) Boat moves forward Boat moves forward (B) Boat moves forward Boat moves backward (C) Boat moves forward Boat does not move (D) Boat moves backward Boat does not move (E) Boat moves backward Boat moves forward This one I'm really clueless. What difference does it make if the ball is moving or caught? I knoew (or think I know) that the boat would move right when the ball is caught, but what happens immeidately after the ball is thrown? I'd try this if I had a heavy ball, a buddy and a boat but I don't live close to any of those. Please help me understand all this stuff.