Chapter 7193SOLUTIONS TO PROBLEMSSection 7.1Systems and EnvironmentsSection 7.2Work Done by a Constant ForceP7.1(a)WFr==°=∆cos..cos..θ16 02 2025 031 9N mJaf(b), (c) The normal force and the weight are both at 90° to the displacement in any time interval.Both do 0work.(d)W∑=++=31 90 031 9..J JP7.2The component of force along the direction of motion isFcos.cos..=°=35 025 031 7N.The work done by this force isr=×cos...∆31 750 01 59 103mJ.P7.3Method One.Let φrepresent the instantaneous angle the rope makes with the vertical asit is swinging up from i=0 to f60 . In an incremental bit of motionfrom angle to φφ+d, the definition of radian measure implies that∆rd=12 m. The angle between the incremental displacement and theforce of gravity is θφ+90. Then coscossin+=−90bg.The work done by the gravitational force on Batman isFIG. 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 .