## College Physics (4th Edition)

(a) An internal energy of $250~J$ is generated. (b) Most of this generated energy went into the slide and the child.
(a) The increase in internal energy is equal to the initial gravitational potential energy of the person at a height of 1.7 meters: $\Delta E = mgh$ $\Delta E = (15~kg)(9.80~m/s^2)(1.7~m)$ $\Delta E = 250~J$ An internal energy of $250~J$ is generated. (b) Since there is friction between the child and the slide, most of the internal energy went into the slide or into the child's clothing initially. Later some of this energy will go into the air as the slide and the clothing cool down. Also, as there was some air resistance during the motion, a small amount of the energy went into the air initially. Most of the generated energy went into the slide and the child initially.