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Homework Help: Power with density problem

  1. Oct 10, 2012 #1
    1. The problem statement, all variables and given/known data
    Sewage at a certain pumping station is raised vertically by 5.50 m at the rate of 1 920 000 liters each day. The sewage, of density 1 050 kg/m3, enters and leaves the pump at atmospheric pressure and through pipes of equal diameter.

    2. Relevant equations

    p = f*d/t = work/time

    3. The attempt at a solution

    Find the output mechanical power of the lift station

    not sure how to get power out of density and liter/day...please help
  2. jcsd
  3. Oct 10, 2012 #2


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    Gold Member

    What if you convert the volume given in litres to cubic meters?
  4. Oct 10, 2012 #3
    what force is doing work when the sewage is being lifted?
  5. Oct 10, 2012 #4
    the pump would be exerting a force upwards while gravity would be exerting a force downwards?
  6. Oct 10, 2012 #5
    right, so how would you go about figuring out the work done by the pump on the sewage?
  7. Oct 10, 2012 #6
    work of the pump = force of the pump * distance
  8. Oct 10, 2012 #7
    so then, what force is the pump applying in order to move the sewage upwards against the force of gravity

    remember that density is mass per unit volume and you were given the volume (a liter is just a cubic meter)
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