1. The problem statement, all variables and given/known data A 2.0kg bob of a pendulum is held at an angle of 55 degrees from the vertical. When released it reaches a maximum speed of 3.5m/s. What is the length of the pendulum arm? 2. Relevant equations Ek = 1/2mv^2 Ep = mgh 3. The attempt at a solution 1/2 * 2 * 3.5 ^ 2 = 12.25 J 12.25 = 2(9.8)h h = 0.625 That's as far as I can get. I know that the length of the pendulum arm is 0.625 plus "length - 0.625" but I'm stuck there. Help would be much appreciated :) Thanks in advance!