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Energy

This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.

State

Energy is the capacity of a system to supply heat or to do work on its surroundings.

Show

Inflating a bicycle tire by hand does work, since the pump moves air against the pressure already inside the tire.

Watch for

"Energy" names a capacity to act, not a substance stored in one fixed location inside an object.