1. The problem statement, all variables and given/known data A 110 kg football player runs at 2.75 m/s directly into a 125 kg player running 2.60 m/s towards him. What is the kinetic energy of the two players if this is a completely inelastic collision. 2. Relevant equations P = m*v Ptotal = Pi - Pf K = 0.5*m*v^2 3. The attempt at a solution Ptotal = 110kg*2.75m/s - 125kg*2.60m/s = -22.5kgm/s k = 0.5*(125kg +110kg)*((-22.5kgm/s)/235kg)^2 = 1.07 J But my textbook's answer is 838 J. I just cannot see where I am wrong.