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Re: What Flows?



I am going to change the subject a bit, from terminology about heat to
terminology about work. The work done by a force on a particle is the dot
product of the force and the displacement of the object. (Obviously a
non-calculus definition.) Occasionally one hears about the" work done
against" a force. For example, "A man lifts a known weight through a
known change in height. How much work does he do against gravity?" What
does this mean? I have never seen a good definition of "work done
against." From the contect I presume that the work done against gravity
is merely nothing more than the negative of the work done by the
gravitational force on the weight. Is that correct? Wouldn't it be best
to avoid using the phrase "work done against?"

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Eugene (Gene) P. Mosca Phone 410-293-6659 (Fax 3729)
Physics Department 410-267-0144 Home
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