HW5-solutions - seunsom (avs294) HW5 bohm (59970) This...

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1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 5.0 points Two 15 N Forces and a 30 N Force act on a hanging box as shown. 15 N 15 N 30 N Will the box experience acceleration? 1. No; it is balanced. 2. Yes; upward. 3. Yes; downward. correct 4. Unable to determine without the angle. Explanation: The horizontal components oF the two 15 N Forces cancel, leaving an upward Force that is less than 30 N. Thus, the net Force on the box is down, causing it to accelerate downward. 002 10.0 points Two Forces are the only Forces acting on a 6 . 1 kg object which moves with an accelera- tion oF 3 . 2 m / s 2 in the positive y direction. One oF the Forces acts in the positive x direc- tion and has a magnitude oF 13 N. What is the magnitude oF the other Force f 2 ? Correct answer: 23 . 4527 N. Explanation: Basic Concepts: s F = m a Solution: f 1 f 2 f v f 2 is the hypotenuse oF a right triangle, so v f 2 = r f 2 + f 1 2 003 (part 1 oF 2) 10.0 points A 32600 kg sailboat experiences an eastward Force 32600 N due to the tide pushing its hull while the wind pushes the sails with a Force oF 57900 N directed toward the northwest (45 westward oF North or 45 northward oF West). What is the magnitude oF the resultant ac- celeration oF the sailboat? Correct answer: 1 . 28167 m / s 2 . Explanation: According to Newton’s Second Law, mva = v F net = v F wind + v F tide . To fnd the magnitude oF the net Force, we draw the parallelogram For vector addition v F wind v F tide v F net θ α NW W E Note that 135 is the angle between the tide and the wind Forces. Use the Law oF Cosines: F 2 net = F 2 wind + F 2 tide - 2 F wind F tide cos θ = (57900 N) 2 + (32600 N) 2 - 2 (57900 N)(32600 N) cos135 = 1 . 74579
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This note was uploaded on 10/22/2008 for the course PHY 302K taught by Professor Kaplunovsky during the Spring '08 term at University of Texas at Austin.

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HW5-solutions - seunsom (avs294) HW5 bohm (59970) This...

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