A hiker plans to swing on a rope across a ravine in the mountains, and to drop when she is just above the far edge.
(a) Find at what horizontal speed should she be moving when she starts to swing?
(b) Below what speed would she be in danger of falling into the ravine? Explain. (The horizontal distance across the ravine is 1.8 m; the vertical length of the rope hanging from the tree above is 4 m)