Adam and Bobby are twins who have the same weight. Adam drops to the ground from a tree at the same time that Bobby begins his descent down a frictionless slide. If they both start at the same height of 4 m above the ground, how do their kinetic energies compare when they hit the ground?
a. Bobby has greater kinetic energy than Adam.
b. Adam has greater kinetic energy than Bobby.
c. They have the same kinetic energy.
d. Bobby has twice the kinetic energy as Ad