Question

A 2.1 kg pendulum bob hangs from a 2 meter string. It is pulled to the side, position A, so that the bob is 125 cm (h on the sketch) above the lowest position, position C. The bob is released and begins to swing. How fast is it moving at that point?

Answer 1

mgh=1/2 mv^2

v=sqrt (2gh) h is 1.25m