# HW 4-1-1 - chun (dc25434) HW04 markert (58840) 1 This...

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chun (dc25434) – HW04 – markert – (58840) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points You new motorcycle weighs 2470 N. The acceleration oF gravity is 9 . 8m / s 2 . What is its mass? Correct answer: 252 . 041 kg. Explanation: Weight is W = mg so m = W g = 2470 N 9 . / s 2 =252 . 041 kg 002 10.0 points AFemalegymnastweighs600N. IF she is hanging stationary From a high bar, how many Forces are acting on her? 1. fve 2. two correct 3. one 4. Four 5. three 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 Al ight ,inextens ib lecordpassesoveral , Frictionless pulley with a radius oF 13 cm. It has a(n) 18 kg mass on the leFt and a(n) 3 . 6kgmassontheright,bothhangingFreely . Initially their center oF masses are a vertical distance 3 m apart. The acceleration oF gravity is 9 . / s 2 . 3m 13 cm ω 18 kg 3 . 6kg At what rate are the two masses accelerat- ing when they pass each other? Correct answer: 6 . 53333 m / s 2 . Explanation: Let : R =13cm , m 1 =3 . , m 2 =18kg , h =3m , and v = ωR. Consider the Free body diagrams 18 kg 3 . T m 2 g 1 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 .A p p l yN e w t o n s second law to m 1 and m 2 respectively and then combine the results: ±or mass 1: ± F 1 : T - m 1 g = m 1 a (1) ±or mass 2: ± F 2 : m 2 g - T = m 2 a (2)

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## This note was uploaded on 09/13/2011 for the course PHYSICS 302K taught by Professor Irenepolycarpou during the Spring '09 term at University of Texas at Austin.

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HW 4-1-1 - chun (dc25434) HW04 markert (58840) 1 This...

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