lecture21[1]

# lecture21[1] - Power; Rotational Energy Power Rotational...

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1 Physics 1D03 - Lecture 21 Power; Rotational Energy Power Rotational work, power, and kinetic energy. Serway 7.5, 8.5, 10.4, 10.8 Suggested Problems : Chapter 8, problem s 31, 39 Chapter 10, problems 25, 27, 47, 49, 52, 53. Physics 1D03 - Lecture 21 Power Power is the rate at which work is done: Average power = Work/time Instantaneous power: Average over an infinitesimal time dt, displacement ds ; the work is dW = F • ds , and power is units: 1 J/s =1 watt (W) v F ds F = = = dt dt dW P

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Physics 1D03 - Lecture 21 Quiz A 100-kg sprinter accelerates from rest to 10 m/s in 4 seconds. His average power output is about: a) 2.5 kW b) 1.25 kW c) 5 kW d) It depends on whether acceleration is constant Physics 1D03 - Lecture 21 Quiz a) Increases with time, starting from zero b) Is a maximum as soon as the elevator starts, then decreases with time c) Is constant after the elevator starts to move. A 2000-kg elevator starts from rest and moves upwards with a
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## This note was uploaded on 12/14/2010 for the course ENGINEERIN 1D03 taught by Professor N.l.mckay during the Spring '10 term at McMaster University.

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lecture21[1] - Power; Rotational Energy Power Rotational...

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