Answers

2016-06-16T05:53:02+08:00
That wil be fall. of course,or i will say your work is done. that is law of interaction.
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What about work done by the gravitational force (the book's weight) and the normal force exerted by the table? Since these forces are perpendicular to the displacement of the book, they do no work on the book! (Think about it - a book lies at rest on a table. Both the weight of the book and the table's normal force act on the book - yet the book never moves! Neither of these forces can change the book's energy!)