Tuesday, 20 September 2011

: Power questions

PFY, p. 120

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power is the rate of doing work

power (in Watrs) = work done (in joules ) / time (in seconds)

1 watt is the rate of working of one joule per second 13. P = e/t
P = 1000/ 5
P = 200 W

14. Wd = F x d P = 600/6 P = 100 W 15. Wd = 3000 x 10 = 30,000 J 30000 / 4 = 7500 watts per second 7.5 kw per second

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