A 21.0 kg child plays on a swing having support ropes
that are 2.30 m long. A friend pulls her back until the
ropes are 39.0 ∘ from the vertical and releases her from
rest.
Part A What is the potential energy for the child just as
she is released, compared with the potential energy at the bottom
of the swing?
Part B How fast will she be moving at the bottom of the
swing?
Part C How much work does the tension in the ropes do as
the child swings from the initial position to the bottom?