A disk-shaped merry-go-round of radius 2.63 m and mass 155 kg rotates freely with an angular speed of 0.744 rev/s. A 59.4-kg person running tangential to the rim of the merry-go-round at 3.99 m/s jumps onto its rim and holds on. Before jumping on the merry-go-round, the person was moving in the same direction as the merry-go-round's rim.
(a) Does the kinetic energy of the system increase, decrease, or stay the same when the person jumps on the merry-go-round?
(b) Calculate the initial and final kinetic energies for this system.