Assume that a person bouncing a ball represents a closed system. Which statement best describes how the amounts of the ball's potential energy and kinetic energy change? A. Both the energy of the ball's potential and kinetic energy decrease.
B. Both the kinetic and the potential energy of the ball increase.
C. The ball's potential energy decreases as it rises and its kinetic energy increases.
D. The ball's kinetic energy increases as it fall's and its potential energy decrease

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.

the answer would be..

b. sucking

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.