1. The problem statement, all variables and given/known data Part A : A 0.5 Kg ball is attached to a cord 80 cm long. The ball is whirled in a vertical circle at a constant speed. If the ball takes 0.4 seconds to go around once, what is the tension in the cord at the top and bottom of the circle? Part B How long does it take for the ball to go around once if the tension in the cord at the top of the circle is zero? 2. Relevant equations v=2Pi*R/T T=m(g+v^2/r) (bottom of the circle) T=m(g-v^2/r) (top of the circle) 3. The attempt at a solution For part A i used both of the circular motion formulas to fin the tension and i got totally different answers from what it suppose to be for top and bottom. Top it suppose to be 93.8N and bottom it suppose to be 104 N i got 92.7N top and 102.7 N bottom. ( I do not know if the answer is a print error). For part B I tried to use v=2Pi*R/T to get the time and i keep getting the same time in part A which is 0.4 secs. But the answer is 1.8 seconds. Can someone explain to be what I'm doing wrong??? thanks!