A large wooden turntable in the shape of a flat uniform disk has a radius of 2.00 {\rm m} and a total mass of 120kg . The turntable is initially rotating at 4.00rad/s about a vertical axis through its center. Suddenly, a 65.0-{\rm kg} parachutist makes a soft landing on the turntable at a point near the outer edge.
a) Find the angular speed of the turntable after the parachutist lands. (Assume that you can treat the parachutist as a particle.)
b) Compute the kinetic energy of the system before the parachutist lands.
c) Compute the kinetic energy of the system after the parachutist lands.
d) Why are these kinetic energies not equal?