Eva is in a closed, dark room. She uses her arm muscles to turn on a lamp. When she moves her hand closer to the lamp, the light heats her hand. The light bounces off the pages of a book and into her eyes. If this room is a closed system, what happens to the total amount of energy in the room? A. It increases, then decreases. B. It increases. C. It decreases. D. It remains constant.



Answer :

AL2006

If the room is really 'closed', so that there's no way for energy to get
in or out of it, then the total amount of energy in the room is constant. 
Energy can't be manufactured in there, and it can't be burned up or
otherwise made to disappear, regardless of what's going on in the room.


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