(a) You throw a ball upward and let it fall to the ground. Your friend drops an identical ball straight down to the ground from the same height. Is the change in kinetic energy of your ball greater than, less than, or equal to the change in kinetic energy of your friend's ball?
(b) Choose the best explanation from among the following:
I. Your friend's ball converts all its initial energy into kinetic energy.
II. Your ball is in the air longer, which results in a greater change in kinetic energy.
III. The change in gravitational potential energy is the same for each ball, which means the change in kinetic energy must be the same also.