Question

Bruce stands on a bank beside a pond, grasps the end of a 20.0-m-long rope attatched to a nearby tree and swings out to drop into the water.If the rope starts at an angle of 35.0 degrees with the vertical, what is Bruce's speed at the bottom of the swing?

Answer 1

Change in potential energy = kinetic energy at bottom

Change in height = h = 20(1-cos 35)

PE = Ke = m g h

(1/2) m v^2 = m g h
so
v = sqrt (2 g h) = sqrt [2 g *20(1-cos35)]

Answer 2

8.41976