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Homework Help: Power Output Question! Thanks!

  1. Nov 11, 2009 #1
    I dont think I have done it right!

    Thanks In Advance!

    1. The problem statement, all variables and given/known data

    Water flows over a 60-m high waterfall at a rate of 2000kg every 5 seconds.
    What is the potential power output of the water fall?

    2. Relevant equations

    KE = 1/2 mV*2

    V = Displacement/time

    P = E/t

    3. The attempt at a solution

    To find out velocity using V = x/t got 12m/s

    Using KE = 1/2 mV*2 1/2 x 2000 x 12*2 = 144000J

    Using P = E/t 144000/5 = 28800W
  2. jcsd
  3. Nov 11, 2009 #2
    No worries I have figured it out

    400 kg/s falls 60 m
    Energy = mgh = 400 x 9.81 x 60 = 235440 J/s = 235440 W = Power

  4. Nov 11, 2009 #3
    Do you understand your mistake in your first attempt? The time you are given is not the time the motion of 2000kg lasts.
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