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25.A man with mass 50kg travels around inside of a sphere of radius 3m on a motor cycle.What is the minimum speed he must have at the lowest point of his path so that he may remain in contact with the sphere at all times? The speed is constant at all times.A. 3.87 m s-1B. 5.48 ms-1C. 11.0 ms -1D. 12.2 ms... 顯示更多 25. A man with mass 50kg travels around inside of a sphere of radius 3m on a motor cycle. What is the minimum speed he must have at the lowest point of his path so that he may remain in contact with the sphere at all times? The speed is constant at all times. A. 3.87 m s-1 B. 5.48 ms-1 C. 11.0 ms -1 D. 12.2 ms -1 29. A trolley of mass 10 kg is projected with an initial speed of 30 ms -1 at the bottom of a smooth circular track of radius 10m. What is the reaction force given by the track when the trolley reach the topmost point of the track ? A. 0 N B. 200 N C. 400 N D. 600 N
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25) Regarding the man and the motorcycle as a point, and let their total mass be m kg, then suppose that the min. speed needed at the lowest point is v, we have: At the top of the path, k.e. is given by: mu2/2 + mg(2 x 3) = mv2/2 (considering mechanical energy conservation) mu2 = mv2 - 12mg Then consider the centripetal force required at the top should be their weight, we have: mu2/3 = mg mu2 = 3mg mv2 - 12mg = 3mg v2 = 15g = 150 v = 12.2 m/s 29) At the top of the track, the k.e. is given by: mu2/2 + mg(2 x 10) = m x 302/2 (considering mechanical energy conservation) u2/2 + 200 = 450 u2 = 500 So the centripetal force is given by: mu2/10 = 10 x 500/10 = 500 N Hence the normal reaction force of the track, R, is given by: R + 10 x 10 = 500 (Sum of normal reaction and weight = centripetal force) R = 400 N
其他解答:A9A3995907B431A4
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25.A man with mass 50kg travels around inside of a sphere of radius 3m on a motor cycle.What is the minimum speed he must have at the lowest point of his path so that he may remain in contact with the sphere at all times? The speed is constant at all times.A. 3.87 m s-1B. 5.48 ms-1C. 11.0 ms -1D. 12.2 ms... 顯示更多 25. A man with mass 50kg travels around inside of a sphere of radius 3m on a motor cycle. What is the minimum speed he must have at the lowest point of his path so that he may remain in contact with the sphere at all times? The speed is constant at all times. A. 3.87 m s-1 B. 5.48 ms-1 C. 11.0 ms -1 D. 12.2 ms -1 29. A trolley of mass 10 kg is projected with an initial speed of 30 ms -1 at the bottom of a smooth circular track of radius 10m. What is the reaction force given by the track when the trolley reach the topmost point of the track ? A. 0 N B. 200 N C. 400 N D. 600 N
最佳解答:
25) Regarding the man and the motorcycle as a point, and let their total mass be m kg, then suppose that the min. speed needed at the lowest point is v, we have: At the top of the path, k.e. is given by: mu2/2 + mg(2 x 3) = mv2/2 (considering mechanical energy conservation) mu2 = mv2 - 12mg Then consider the centripetal force required at the top should be their weight, we have: mu2/3 = mg mu2 = 3mg mv2 - 12mg = 3mg v2 = 15g = 150 v = 12.2 m/s 29) At the top of the track, the k.e. is given by: mu2/2 + mg(2 x 10) = m x 302/2 (considering mechanical energy conservation) u2/2 + 200 = 450 u2 = 500 So the centripetal force is given by: mu2/10 = 10 x 500/10 = 500 N Hence the normal reaction force of the track, R, is given by: R + 10 x 10 = 500 (Sum of normal reaction and weight = centripetal force) R = 400 N
其他解答:A9A3995907B431A4
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