191_Physics ProblemsTechnical Physics

191_Physics ProblemsTechnical Physics - Chapter 7 SOLUTIONS...

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Chapter 7 193 SOLUTIONS TO PROBLEMS Section 7.1 Systems and Environments Section 7.2 Work Done by a Constant Force P7.1 (a) WF r == ° = cos . . cos . . θ 16 0 2 20 25 0 31 9 N m J af (b), (c) The normal force and the weight are both at 90° to the displacement in any time interval. Both do 0 work. (d) W =+ + = 31 9 0 0 31 9 .. J J P7.2 The component of force along the direction of motion is F cos . cos . . = 35 0 25 0 31 7 N . The work done by this force is r = × cos . . . 31 7 50 0 1 59 10 3 m J . P7.3 Method One. Let φ represent the instantaneous angle the rope makes with the vertical as it is swinging up from i = 0 to f 60 . In an incremental bit of motion from angle to φφ + d , the definition of radian measure implies that rd = 12 m . The angle between the incremental displacement and the force of gravity is θφ + 90 . Then cos cos sin + = 90 bg . The work done by the gravitational force on Batman is FIG. P7.3
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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