A pendulum bob of mass m swinging from the end of a light string of length L = 1.89 m. The bob has speed of v0 = 9.42 m/s when the string makes an angle θ0 = 33.9° with the vertical. What is the speed (in m/s) of the bob when it is at its lowest point?

Answer 1

the speed of the bob is increased by the change in height

h = 1.89 m [1 - cos(33.9º)]

1/2 m v0^2 + m g h = 1/2 m v^2 ... v^2 = v0^2 + 2 g h