[SOLVED] Find Tension for Centripetal Motion George of the Jungle swings on a vine 6.5 meters long. What is the tension in the vine if George, whose mass is 75 kg, is moving at 2.4 m/s when the the vine is vertical? I tried using the equation F = ma and a = v^2/r. I plugged the 2nd one into the first but it didn't come out with the right answer. F = (75)(2.4^2)/(6.5) = 66.46 N when the answer should actually be 801.46 N. I know gravity should go somewhere in there too but I'm not sure where. I tried multiplying 66.46 by 9.8 m/s^2 and ended up with 651.32. What am I doing wrong?