HW 7-3-solutions

# HW 7-3-solutions - madrid (tmm2353) HW 7-3 Antoniewicz...

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Unformatted text preview: madrid (tmm2353) HW 7-3 Antoniewicz (56445) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A certain motor is capable of doing 2200 J of work in 14 s. What is the average power output of the motor? Correct answer: 157 . 143 W. Explanation: P = W t = 2200 J 14 s = 157 . 143 W . 002 (part 1 of 2) 10.0 points If you follow a diet of 2000 food calories per day (2000 kilocalories), what is your average power consumption in watts? (1 calorie=4.2 J.) Correct answer: 97 . 2 W. Explanation: P = (2000 cal)(1000)(4 . 2 J) (24 hr)(3600 s) = 97 . 2 W. 003 (part 2 of 2) 10.0 points You can produce much higher power for short periods of time. Suppose you run up a flight of stairs of height h = 4 m in t = 13 s. Estimate your average power output if your total body mass is m = 60 kg. You can neglect friction or any other dissipative forces in your calculation. Use g = 9 . 8 m / s 2 . Correct answer: 180 . 923 W. Explanation: P = mg h t = (60 kg)(9 . 8 m / s 2 )(4 m) 13 s = 180 . 923 W . 004 (part 1 of 3) 10.0 points Consider a horizontal spring-mass system with stiffness 205 N / m and mass 0 . 9 kg. The system is released with an initial compression of the spring of 0 . 1 m and an initial speed of the mass of 2 m / s. What is the maximum stretch of the spring during the motion, neglecting friction?...
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## HW 7-3-solutions - madrid (tmm2353) HW 7-3 Antoniewicz...

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