A pendulum consists of a 2.0 kg stone swinging on a 4.5 m string of negligible mass. The stone has a speed of 8.0 m/s when it passes its lowest point. (a) What is the speed when the string is at `60^(@)` to the vertical ? (b) What is the greatest angle with the vertical that the string will reach during the stone's motion ? (c) If the potential energy of the pendulum-Earth system is taken to be zero at the stone's lowest point, what is the total mechanical energy of the system ?

Answer

`(a) 4.5 m//s; (b) 74^(@); (c) 64J`