Conservation of energy --swinging vine. I am not sure how to do this question. I tried doing it but the answer differs from the book. Here it is: "A 17m long vine hangs vertically from a tree on one side of a 10 m wide hole. A person runs up, hoping to grab the vine, swing over the hole, and drop vertically off the vine to land on the other side. At what minimum speed must he be running?" So, since this is in the conservation of energy, you have K2 + U2 = K1 + U1 I really have no clue how I can use this to solve the problem. Can anyone tell me how to get started, which equation I should use? Thanks.