1. The problem statement, all variables and given/known data A 55.0 g Super Ball traveling at 30.0 m/s bounces off a brick wall and rebounds at 21.0 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 5.00 ms, what is the magnitude of the average acceleration of the ball during this time interval? 3. The attempt at a solution I know how to solve, but dont understand why is it solve this way. F = m a F = m dv/dt Fdt = mdv F(5E-3) = (55E-3)(21-(-30)) F = 561 N a = F/m = 561/55E-3 a = 10200 m/s² I highlighted the part that I don't understand v1 = 25m/s , but when it rebounces , wouldn't the velocity changes then vf should be different in this case from a ball that is just going straight without hitting a barrier. Can someone explain it to me? thanks!