Solve the each part of given question:
Question: Kids at a swimming hole swing over the water on a tire swing (essentially a simple pendulum) and then drop in the water. If the tire+kid take 2.1 seconds to swing from the launching point to its farthest point over the water,
Part A: How long will it take the empty tire to return for the next kid?
Part B: How long is the rope?
I need help to find how long it takes the empty tire to return for the next kid.