I have been having trouble with three problems from various homeworks. 1. A 500 g ball swings in a vertical circle at the end of a 1.5-m-long string. When the ball is at the bottom of the circle, the tension in the string is 15 N. What is the speed of the ball at that point? 2.It is proposed that future space stations create an artificial gravity by rotating. Suppose a space station is constructed as a 1000-m-diameter cylinder that rotates about its axis. The inside surface is the deck of the space station. What rotation period will provide "normal" gravity? 3.A 500 g steel block rotates on a steel table while attached to a 2.0-m-long massless rod. Compressed air fed through the rod is ejected from a Inozzle on the back of the block, exerting a thrust force of 3.5 N. The nozzle is 70* from the radial line. The block starts from rest. What is the block's angular velocity after 10 rev? What is the tension in the rod after 10 rev? If someone could help me out with these problems I would really appreciate it.