1. The problem statement, all variables and given/known data A .10 kg solid rubber ball is attached to the end of a .80 m length of light thread. The ball is swung in a vertical circle. Point P, the lowest point of the circle, is .20 m above the floor. The speed of the ball at the top of the circle is 6.0 m/s, and the total energy of the ball is kept constant. a) Determine the total energy of the ball, using the floor as the zero point for gravitational potential energy. b) Determine the speed of the ball at point P, the lowest point of the circle. 2. Relevant Equations 1/2mv^2 = KE mgh = PE E1=E2 3. The attempt for a solution I'm thinking for part A, that I'd use the mgh=PE equation. But I also notice that the ball is moving! Would it be KE + PE = TE? I really figured that, but I could be wrong. For part B, I just know that energy at the top has to equal it at the bottom. I don't know where to go from that.