1. The problem statement, all variables and given/known data We have a collision between a finite mass steel ball and an infinite mass steel wall and must find the maximum compression if we are given the mass of the ball, the initial speed and the constant b (See eq. below). 2. Relevant equations We know that the maximum compression for two spheres colliding is given by Em=((5/4b)uv^2)^5/2 where v is the initial velocity upon collision and u is the reduced mass u=m1m2/(m1+m2). b is a constant. 3. The attempt at a solution Now my only question is what to use as the reduced mass. Mathematically by putting in infinity as m2 we get a reduced mass of 1. Is this correct?