Can any one help me with these two problems? Thank-you 1.) Two carts with masses of 15.5 kg and 6.0 kg, respectively, move in opposite directions on a frictionless horizontal track with speeds of 7.0 m/s and 2.0 m/s, respectively. The carts stick together after colliding head-on. Find the final speed of the two carts. For this one, I know one of the velocities has to be negative, but which one? Does it matter? 2.) A 1.80 kg skateboard is coasting along the pavement at a speed of 7.0 m/s when a 0.400 kg cat drops from a tree vertically downward onto the skateboard. What is the speed of the skateboard-cat combination. For this problem I know that the cat's accleration will be -9.8, is that correct?