A 22.9-kg child is on a swing attached to ropes that are L = 1.33 m long. Take the zero of the gravitational potential energy to be at the position of the child when the ropes are horizontal.

Question

Part A)The child's gravitational potential energy when the child is at the lowest point of the circular trajectory=-298.8 J
Part B)Determine the child's gravitational potential energy when the ropes make an angle of 45.0° relative to the vertical.
and
Based on the results in part a) and b), which position has the higher potential energy?
the position in part b) has greater potential energy
the position in part a) has greater potential energy

Answer 1

U = m g h

A)
U = 0 - 22.9 * 9.81 * 1.33
= -298.8 J
B)
U = 0 - 22.9 * 9.81 * cos 45
= -158.9
C)
B is higher than A and has higher (less negative) potential energy.