[SOLVED] Another use for a tennis ball 1. The problem statement, all variables and given/known data To test the quality of a tennis ball, you drop it onto the floor from a height of 4.93 m. It rebounds to a height of 2.68 m. If the ball is in contact with the floor for 12.3 ms, what is its average acceleration during that contact? 2. Relevant equations 3. The attempt at a solution v1 = -sqrt(-2(g)(4.93m)) = -9.83 m/s v2 = sqrt(2(g)(-2.68+4.93)) = 6.64 m/s Average acel = v2-v1/delta time = (6.64-(-9.83))/12.3x10^(-3)ms = 1.34 m/s^2? The answer isn't correct but I have no idea where I'm going wrong.