05_InstSolManual_PDF_Part18

05_InstSolManual_PDF_Part18 - constant speed the...

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5.39. Set Up: For constant speed, Apply with in the direction of motion of the box. Solve: (a) The free-body diagram for the box is given in Figure 5.39. gives and Figure 5.39 (b) and Reflect: In (b) the friction force and the acceleration are directed opposite to the motion. Since and are in oppo- site directions, the box slows down. 5.40. Set Up: Once the crate has started to move friction is kinetic. The free-body diagram for the crate is given in Figure 5.40. is the force the worker applies. The crate has mass Figure 5.40 Solve: so The force F to get the box moving is After the box is moving, friction is gives and 5.41. Set Up: The free-body diagram for the box is given in Figure 5.41. When the box is either at rest or sliding at
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Unformatted text preview: constant speed, the acceleration of the box is zero. Use coordinates as shown, with the x axis parallel to the incline. The weight mg has been resolved into its x and y components. Figure 5.41 mg sin u mg cos u u mg y x n f a 5 F 2 f k m 5 293 N 2 200 N 48.6 kg 5 1.91 m / s 2 F 2 f k 5 ma g F x 5 ma x f k 5 m k n 5 1 0.420 21 476 N 2 5 200 N. F 5 m s n 5 1 0.615 21 476 N 2 5 293 N. n 5 w . g F y 5 ma y y x w n f k F m 5 w / g 5 48.6 kg. F S v S a S a x 5 2 f k m 5 2m k g 5 2 1.96 m / s 2 . 2 f k 5 ma x . P 5 y x mg n f k P v P 5 f k 5 m k mg 5 1 0.200 21 11.2 kg 21 9.80 m / s 2 2 5 22.0 N. P 2 f k 5 g F x 5 ma x 1 x g F x 5 ma x a x 5 0. n 5 mg . 5-18 Chapter 5...
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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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