Bob, of mass m, drops from a tree limb at the same time that esther, also of mass m, begins her descent down a slide. they both start at the same height above the ground. if there is friction on the slide, which of the following is true about their kinetic energies as they reach the ground? a. esther's kinetic energy is greater than bob's. b. bob's kinetic energy is greater than esther's. c. they have the same kinetic energy. d. the answer depends on the shape of the slide. e. the answer depends on the length of the slide.