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Homework Help: Power question.

  1. Oct 4, 2004 #1
    Water flows over a section of Niagara Falls at
    a rate of 1.38 x 10^6 kg/s and falls 32 m.
    The acceleration of gravity is 9.8 m/s2 .
    How many 80 W bulbs can be lit with this
    power?
     
  2. jcsd
  3. Oct 4, 2004 #2
    Force = Mass*Acceleration, which in this case will be in newtons.
    P = Force*distance / time, note that force*distance is also called "work" and the units of work are "Joules". A watt is Joules over time, which is exactely what this equation comes up with.

    That should be all you need to know.
     
  4. Oct 4, 2004 #3
    thanks for the help.
     
  5. Oct 5, 2004 #4
    If i am not mistaken, here we have to use Newton's second law in real form that's
    f=d/dt(m*v)
    here velocity is not the variable but the mass (check kg/s)
    work done = f*d/time

    you can do the rest.
     
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