08_InstSolManual_PDF_Part8

08_InstSolManual_PDF_Part8 - v A , f 5 29.3 m / s. 0.500 v...

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8.29. Set Up: Use coordinates where is east and is south. The system of two cars before and after the collision is sketched in Figure 8.29. Neglect friction from the road during the collision. The enmeshed cars have mass Figure 8.29 Solve: There are no external horizontal forces during the collision, so and (a) gives and (b) gives And then with Reflect: Momentum is a vector and we must treat each component separately. 8.30. Set Up: The before and after diagrams are given in Figure 8.30 and the choice of coordinates is indicated. Each puck has mass m . Figure 8.30 Solve: (a) gives and gives and Combining these two equations gives and Then (b) 19.6% of the original kinetic energy is dissipated during the collision. D K K i 5 K f 2 K i K i 5 K f K i 2 1 52 0.196. K f K i 5 v A , f 2 1 v B , f 2 v A , i 2 5 1 29.3 m / s 2 2 1 1 20.7 m / s 2 2 1 40.0 m / s 2 2 5 0.804. K f 5 1 2 m v A , f 2 1 1 2 m v B , f 2 . K i 5 1 2 m v A , i 2 . v B , f 5 1 0.500 0.707 2 1 29.3 m / s 2 5 20.7 m / s.
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Unformatted text preview: v A , f 5 29.3 m / s. 0.500 v A , f 5 40.0 m / s 2 0.866 v A , f 0.500 v A , f 5 0.707 v B , f . 5 m v A , f sin 30.0 2 m v B , f sin 45.0 P i, y 5 P f, y 0.707 v B , f 5 40.0 m / s 2 0.866 v A , f . 40.0 m / s 5 0.866 v A , f 1 0.707 v B , f m v A , i 5 m v A , f cos 30.0 1 m v B , f cos 45.0. P i, x 5 P f, x x y B A v A ,i x y A B v A ,f v B ,f 30 45 Before After v A , i 5 5.2 m / s. v f 5 7.1 m / s, 1 2000 kg 2 v A , i 5 1 3500 kg 2 v f cos 65. P i, y 5 P f, y v f 5 7.1 m / s 1 1500 kg 21 15 m / s 2 5 1 3500 kg 2 v f sin 65 P i, x 5 P f, x P i, y 5 P f, y . P i, x 5 P f, x B A A 1 B v f sin65 v f cos65 v f v A ,i Before After 65 15m / s x y 2000 kg 1 1500 kg 5 3500 kg. 1 y 1 x 8-8 Chapter 8...
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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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