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Unformatted text preview: pasha (sep635) – HW 71 – Antoniewicz – (56445) 1 This printout should have 8 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A horizontal spring with sti ff ness 0 . 5 N / m has a relaxed length of 11 cm. A mass of 25 g is attached and you stretch the spring to a total length of 29 cm. The mass is then released from rest and moves with little friction. What is the speed of the mass at the moment when the spring returns to its relaxed length of 11 cm? Correct answer: 0 . 804984 m / s. Explanation: From the Conservation of Energy (C.E.) principle, E i = E f , where E i = 1 2 k ( ` ` ) 2 , and E f = 1 2 mv 2 f . This implies that v f = ( ` ` ) r k m = (29 cm 11 cm) s . 5 N / m 25 g = . 804984 m / s . Remember to convert all quantities to ap propriate units. 002 10.0 points A spring has a relaxed length of 5 cm and a sti ff ness of 105 N / m. How much work must you do to change its length from 2 cm to...
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This note was uploaded on 11/17/2011 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas.
 Fall '08
 Turner
 Energy

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