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Unformatted text preview: reddy (ar38357) Rotational Kinetic Energy clancy (SCI4112) 1 This printout should have 6 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A 0 . 25 m power sawblade has a mass of 0 . 5 kg distributed uniformly as in a disc. What is the rotational kinetic energy at 3600 rpm (revolutions per minute)? 1. 3 . 6 10 1 J 2. 2 . 6 10 3 J 3. 8 . 9 10 1 J 4. 1 . 1 10 3 J correct 5. 9 . 1 10 2 J Explanation: Let : r = 0 . 25 m , m = 0 . 5 kg , and = 3600 rpm . The moment of inertia of a disk of uniform density is I = 1 2 mr 2 . The rotational kinetic energy of the saw blade is then K rot = 1 2 I 2 = 1 2 parenleftbigg 1 2 mr 2 parenrightbigg 2 = 1 4 (0 . 5 kg)(0 . 25 m) 2 (3600 rpm) 2 parenleftbigg 2 rev parenrightbigg 2 parenleftbigg 1 min 60 s parenrightbigg 2 = 1110 . 33 J . 002 10.0 points The net work done in accelerating a propeller from rest to an angular speed of 214 rad/s is 2892 . 2 J....
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This note was uploaded on 11/21/2010 for the course PHYS 12231 taught by Professor Sontar during the Fall '10 term at Ill. Chicago.
 Fall '10
 Sontar
 Physics, Energy, Kinetic Energy, Mass, Power

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