solutions2B

solutions2B - PHYS 152 EXAM 2B SOLUTIONS PROBLEM 1 (A) fk =...

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PHYS 152 EXAM 2B SOLUTIONS Fall Semester 2008 PROBLEM 1 (A) f k = μ k m 1 g cos θ = 0.68(16 kg)(9.8 m/s 2 )cos37° = 85.15 N (B) Σ F x = T f k m 1 g sin θ = 0 T = 85.15 N + (16 kg)(9.8 m/s 2 )sin37° = 179.5 N (C) Σ F y = Mg T = 0 M = T / g = 18.32 kg PROBLEM 2 (A) K O = 0.5(3 kg)(6 m/s) 2 = 54 J (B)   4 0 2 3 3 7 4 4 1 2 4 0 3 6 ) 12 7 ( x x x dx x x x W = -10.67 J (C) K = K O + W 0.5(3 kg) v 2 = 54 J – 10.67 J v = 5.37 J PROBLEM 3 (A) E initial = mgy = (150 kg)(9.8 m/s 2 )(3 m) = 4410 J (B) E final = 2 2 1 kx = 0.5(1900)(1.8 m) 2 = 3078 J W fric = E final E initial = –1332 J (C) W fric = – μ k mgs mgs W μ fric k = 0.453 (D) K = E final 0.5(150 kg) v 2 = 3078 J v = 6.41 m/s
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