hw15(1) - lenoir (wml297) homework 15 Turner (58220) 1 This...

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Unformatted text preview: lenoir (wml297) homework 15 Turner (58220) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A hot rod of mass 1100 kg, starting from rest reaches a speed of 150 m / s in only 26 . 1 s. What is the average output power? 1. . 00632184 MW 2. . 948276 MW 3. . 474138 MW correct 4. . 0181662 MW 5. . 000121108 MW Explanation: The average output power is equal to the kinetic energy acquired divided by the total time, so P = 1 2 mv 2 t = (1100 kg) (150 m / s) 2 2 (26 . 1 s) mW 10 6 W = 0 . 474138 MW 002 10.0 points A car with a mass of 1 . 09 10 3 kg starts from rest and accelerates to a speed of 17.1 m/s in 18.1 s. Assume that the force of resistance remains constant at 310.4 N during this time. What is the average power developed by the cars engine? Correct answer: 11458 . 5 W. Explanation: Let : m = 1 . 09 10 3 kg , v f = 17 . 1 m / s , t = 18 . 1 s , and F r = 310 . 4 N . v f = a t and x = 1 2 a ( t ) 2 since v i = 0 m/s, and F = m a + F r , so P = F x t = F 1 2 a ( t ) 2 t = F a t 2 = ( m a + F r ) v f 2 = parenleftBig m v f t + F r parenrightBig v f 2 = bracketleftbigg (1090 kg)(17 . 1 m / s) 18 . 1 s + 310 . 4 N bracketrightbigg 17 . 1 m / s 2 = 11458 . 5 W . 003 10.0 points A car weighing 8800 N moves along a level highway with a speed of 90 km / h. The power of the engine at this speed is 67 kW. The car encounters a hill inclined at an angle of 6 with respect to the horizontal....
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hw15(1) - lenoir (wml297) homework 15 Turner (58220) 1 This...

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