ch6 problem30

Physics: Principles with Applications

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Chapter 6, Problem 30 Question Problem (a) The gravitational potential energy of an object is the product of the weight of the object and its height above some reference level. (a) Choose the ground as our reference level. Let be the height of the book from the ground. Find the potential energy of the book relative to the ground. Substitute 2.10 kg for , for , and 2.20 m for . Thus, the potential energy of the book relative to the ground is . (b) Choose the top of the person s head as our reference level. Let be the height of the person relative to the ground. The height of the book above the person s head is given by the relation . Find the potential energy
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Unformatted text preview: of the book relative to the person ’ s head using the equation . Substitute 2.10 kg for , for , 2.20 m for and 1.60 m for . Thus, the potential energy of the book relative to the person ’ s head is . (c) The work done by the person to lift the book to a height above the ground is given by the equation . The height of the book above the ground is equal to . Rewrite the equation for work done. The work done by the person to lift the book is equal to the potential energy of the book when it is at height of 2.20 m above the ground. Thus, the work done by the person is related to the answer in part (a). http://www.hwproblems.com/cgi-bin/book.cgi?bookid=0044&cptn=6pr30&id=489216 [2/4/2008 4:32:12 PM]...
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This document was uploaded on 02/05/2008.

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