1. The problem statement, all variables and given/known data So we are doing a lab that is basically finding the coefficeint of restituion, what we did in this lab is drop a tennis ball from an initial height (recorded that height) and timed it until it stopped bouncing. So we have the time it stopped bouncing at and the height, and now we have to find the coefficeint of restution. So I am guessing the two bodies in this situation is the ball, and the floor? 2. Relevant equations e = (v2final - v1final / v2initial - vinitial) 3. The attempt at a solution So i know that v2f - v1f is equal to the velocity of seperation, which is the veloicty of the ball and second body after the collision, and v2i - v1i is the velocity of the ball and second body before the collision. Before i move further i would like to have help figuring out the second body in this collision.