1. The problem statement, all variables and given/known data For an initial velocity of V0, what is the velocity of the ball as it passes the point A on its way up, where OA is 1/3 the maximum height. V0 = 10m/s t = 1s (2s total for the ball to come back down) maximum height = 5m initial displacement x0 = 0m 2. Relevant equations Vf^2 = V0^2 + 2a(x - x0) 3. The attempt at a solution I'm assuming point O is the ground. If point OA is 1/3 of the maximum height then, it is 5/3m. My confusion is what point A should be. Is it some arbitrary point that is just deemed "A"? The answers are in terms of vA (velocity as the ball passes through point A) = initial velocity times a constant. The other thing I can think of is that I am wrong for setting point O at 0. Am I supposed to go another "O" distance from OA to get to point A? I know this answer is yahoo answers or something, but I refrained from just looking at the answer because I really want to understand what is going on.