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Unformatted text preview: yoon (jy4326) – HW04 – markert – (58840) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points You new motorcycle weighs 2440 N. The acceleration of gravity is 9 . 8 m / s 2 . What is its mass? Correct answer: 248 . 98 kg. Explanation: Weight is W = mg so m = W g = 2440 N 9 . 8 m / s 2 = 248 . 98 kg 002 10.0 points A female gymnast weighs 600 N. If she is hanging stationary from a high bar, how many forces are acting on her? 1. three 2. two correct 3. four 4. five 5. one Explanation: Two forces act on her: gravity pulls down on her and the bar pulls up on her. These forces are equal (600 N), but act in opposite directions. 003 (part 1 of 2) 10.0 points A light, inextensible cord passes over a light, frictionless pulley with a radius of 11 cm. It has a(n) 14 kg mass on the left and a(n) 8 . 9 kg mass on the right, both hanging freely. Initially their center of masses are a vertical distance 2 . 3 m apart. The acceleration of gravity is 9 . 8 m / s 2 . 2 . 3 m 11 cm ω 14 kg 8 . 9 kg At what rate are the two masses accelerat ing when they pass each other? Correct answer: 2 . 18253 m / s 2 . Explanation: Let : R = 11 cm , m 1 = 8 . 9 kg , m 2 = 14 kg , h = 2 . 3 m , and v = ω R. Consider the free body diagrams 14 kg 8 . 9 kg T T m 2 g m 1 g a a Since the larger mass will move down and the smaller mass up, we can take motion downward as positive for m 2 and motion up ward as positive for m 1 . Apply Newton’s second law to m 1 and m 2 respectively and then combine the results: For mass 1: summationdisplay F 1 : T m 1 g = m 1 a (1) For mass 2: summationdisplay F 2 : m...
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This note was uploaded on 01/08/2010 for the course CH 53675 taught by Professor Bocknack during the Fall '09 term at University of Texas.
 Fall '09
 BOCKNACK
 Organic chemistry

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