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Physics exercises_solution: Chapter 08

Bộ tài liệu bài tập tham khảo môn vật lý bậc đại học bằng tiếng anh Chapter 08 | 8.1 a 10 000 kg 12.0 m s 1.20 x 105 kg m s. b i Five times the speed 60.0 ms. ii V5 12.0 m s 26.8 ms. 8.2 See Exercise 8.3 a the iceboats have the same kinetic energy so the boat with the larger mass has the larger magnitude of momentum by a factor of 4 2m m 42. 8.3 a r 1 2 K mv 2 22 1 m2v2 2 m 1 pL 2 m 2 2 p P b From the result of part a for the same kinetic energy so the larger mass m1 m2 baseball has the greater momentum pbird pball 40.040 0.145 0.525. From the result of part b for the same momentum K1m1 K2m2 so K1 w1 K2w2 the woman with the smaller weight has the larger kinetic energy. Kman K woman 450 700 0.643. 8.4 From Eq. 8.2 Px mvx 0.420 kg 4.50m s cos 20.0 1.78 kg m s Py mvy 0.420 kg 4.50 ms sin 20.0 0.646 kg ms. 8.5 The y-component of the total momentum is 0.145 kg 1.30 ms 0.0570 kg - 7.80 ms -0.256 kg ms. This quantity is negative so the total momentum of the system is in the - y -direction. 8.6 From Eq. 8.2 py - 0.145 kg 7.00 m s -1.015 kg ms and Px 0.045 kg 9.00 ms 0.405 kg m s so the total momentum has magnitude P 7PX Py 7 - 0.405 kg ms 2 -1.015 kg ms 2 1.09 kg ms 10 nt 1 o fri zù 1 I 1-015 1 2 QO 11 fin ex 4 1 1 zù t mil iû 4 1 1 zù 1 t 4 1 i 4- -fi i-t 4 1 vi i 1 4-1- and is at an angle arctan -68 using the value oi the arctangent function in the fourth quadrant px 0 py 0 . 8.7 f 0.0450kg 25 ms 563 N. The weight of the ball is less than half a newton so the Ai 2.00 lo 3 s b weight is not significant while the ball and club are in contact. 8.8 a The magnitude of the velocity has changed by 45.0m s - - 55.0 ms 100.0 ms and so the magnitude of the change of momentum is 0.145 kg 100.0 ms 14.500 kg ms to three figures. This is also the magnitude of the impulse. b From Eq. 8.8 the magnitude of the average applied force is 14-500kgf s 7.25 x 103N. 2.00x10-3s 8.9 a Considering the x-components P2 P1 J 0.16 kg 3.00 ms 25.0 N x 0.05 s 1.73 kg ms and the velocity is 10.8 ms in the x-direction. b p 2 0.48 kg m s -12.0 N 0.05 s -0.12 kg ms and the velocity is .