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Unformatted text preview: ikram (ai2734) hw1013 Swinney (58785) 1 This printout should have 9 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A small air compressor operates on a 2 . 7 hp (horsepower) electric motor for 9 . 6 hours a day. How much energy is consumed by the motor daily? 1 hp equals about 750 watts. Correct answer: 6 . 9984 10 7 J. Explanation: Let : P = 2 . 7 hp , and t = 9 . 6 h . P = 2 . 7 hp 750 W hp = 2025 W = 2025 J / s , so W = P t = (2025 J / s) (9 . 6 h) 3600 s 1 h = 6 . 9984 10 7 J . 002 (part 2 of 2) 10.0 points If electricity costs 12 cents per kilowatthour, how much does it cost to run the compressor each day? Correct answer: 233 . 28 cents. Explanation: The energy in kilowatthours is given by: E = P t = (2 . 025 kW) (9 . 6 h) = 19 . 44 kW h , Cost = (19 . 44 kW h) (12 cents / kW h) = 233 . 28 cents . At 12 cents per kW h, it would cost 233 . 28 cents to run the compressor for a day....
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This note was uploaded on 02/02/2010 for the course PHY 301 taught by Professor Swinney during the Spring '07 term at University of Texas at Austin.
 Spring '07
 Swinney
 mechanics

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