05_InstSolManual_PDF_Part31 - Applications of Newtons Laws...

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Solve: (a) gives gives (b) gives gives (c) gives gives Reflect: In each stage the upward force is greater than the downward force, the acceleration is upward, opposite to and the speed decreases. 5.76. Set Up: Constant speed means Use Newton’s 3 rd law to relate forces on A and on B . Solve: (a) Treat A and B as a single object of weight The free-body diagram for this com- bined object is given in Figure 5.76a. gives gives Figure 5.76 (b) The free-body force diagrams for blocks A and B are given in Figure 5.76b. n and are the normal and friction forces applied to block B by the tabletop and are the same as in part (a). is the friction force that A applies to B . It is to the right because the force from A opposes the motion of B . is the downward force that A exerts on B . is the friction force that B applies to A . It is to the left because block B wants A to move with it. is the normal force that block B exerts on A . By Newton’s third law, and these forces are in opposite directions. Also,
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This note was uploaded on 03/06/2009 for the course PHYS 114 taught by Professor Shoberg during the Spring '07 term at Pittsburg State Uiversity.

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