1. The problem statement, all variables and given/known data Given mass = 90kg distance = 20m above sea level. Find his potential and kinetic energy at the top of the cliff, at what point in his leap is his kinetic energy 450 J and at what speed does he enter the water? 2. Relevant equations 3. The attempt at a solution I can solve for PE and KE at the top of the cliff. Have trouble calculating when his KE = 450 J and his velocity entering the water.