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Unformatted text preview: Create assignment, 00224, Homework 5, Feb 28 at 6:39 pm 1 This printout should have 9 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. The due time is Central time. Lengthening a Wire 02 27:03, trigonometry, numeric, > 1 min, nor mal. 001 A wire with a resistance R is lengthened to 1 . 25 times its original length by pulling it through a small hole. Find the resistance of the wire after it is stretched. Correct answer: 1 . 5625 R . Explanation: Let : ‘ = 1 . 25 ‘ . The volume V of the wire is given by V = ‘ A, where ‘ is the length of the wire and A is the crosssectional area. When the wire is stretched to a length ‘ , the volume will re main the same. The new crosssectional area is then, ‘ A = ‘ A A = ‘ A ‘ = ‘ A 1 . 25 ‘ = A 1 . 25 . The resistance of a conductor of resistivity ρ is given by R = ρ ‘ A , so R R = ρ ‘ A ρ ‘ A = ‘ A ‘ A = (1 . 25 ‘ ) A ‘ µ A 1 . 25 ¶ = (1 . 25) 2 . Thus R = (1 . 25) 2 R = 1 . 5625 R . keywords: Serway CP 17 64 27:03, trigonometry, numeric, > 1 min, nor mal....
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 Spring '10
 Avram
 Physics, Work, Correct Answer, crosssectional area

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