# 10 - hernandez(ejh742 oldhomework 10 Turner(58120 This...

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hernandez (ejh742) – oldhomework 10 – Turner – (58120) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points The system is in equilibrium and the pulleys are Frictionless and massless. 6 kg 9 kg 9 kg 1 2 3 T ±ind the Force T . The acceleration oF grav- ity is 9 . 8 m / s 2 . Correct answer: 323 . 4 N. Explanation: Let : m 1 = 6 kg , m 2 = 9 kg , and m 3 = 9 kg . m 1 m 2 m 3 1 2 3 T T 4 T 3 T 3 T 3 T 2 T 1 T 1 The mass m 1 defnes the tension T 1 : T 1 = m 1 g . At pulley 3, T 1 acts down on either side oF the pulley and T 2 acts up, so T 2 = 2 T 1 = 2 m 1 g . At the mass m 2 , T 3 acts up, and m 2 g and T 2 act down, so T 3 = m 2 g + T 2 = m 2 g + 2 m 1 g . At pulley 2, T 3 acts up on either side oF the pulley and T 4 acts down, so T 4 = 2 T 3 = 2 m 2 g + 4 m 1 g . At the mass m 3 , T 4 = T + m 3 g T = T 4 m 3 g = (2 m 2 + 4 m 1 m 3 ) g = [2 (9 kg) + 4 (6 kg) (9 kg)] (9 . 8 m / s 2 ) = 323 . 4 N . keywords: 002 (part 1 oF 2) 10.0 points A book is at rest on an incline as shown below. A hand, in contact with the top oF the book, produces a constant Force F hand vertically downward. F hand Book The Following fgures show several attempts at drawing Free-body diagrams For the book. Which fgure has the correct directions For each Force? The magnitudes oF the Forces are not necessarily drawn to scale. 1. weight Friction Force normal

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hernandez (ejh742) – oldhomework 10 – Turner – (58120) 2 2. weight friction normal force 3. normal friction weight force 4. normal force friction weight 5. weight force friction normal correct 6. weight force normal friction 7. weight normal friction force 8. weight force normal friction Explanation: The normal force points perpendicular to the surface of the inclined plane. The weight force points down. The F hand also points down. The friction force keeps the book from
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## This note was uploaded on 06/14/2011 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas.

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10 - hernandez(ejh742 oldhomework 10 Turner(58120 This...

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