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Homework Help: Energy niagra falls problem water

  1. Oct 20, 2007 #1
    1. The problem statement, all variables and given/known data

    In the Niagara Falls hydroelectric generating plant, the energy of falling water is converted into electricity. The height of the falls is about 45 meters. Assuming that the energy conversion is highly efficient, approximately how much energy is obtained from one kilogram of falling water? Therefore, approximately how many kilograms of water must go through the generators every second to produce a megawatt of power (106 watts)?


    2. Relevant equations

    Gravitational energy = (mass) × g × (height).

    3. The attempt at a solution

    I tried to find energy based on the fact one drop of water is one gram.
    I ended up pluging in the values and got (45)(9.8) = 441
    I found this to be incorrect.
    Not sure how to relate mass to seconds to energy to height....
  2. jcsd
  3. Oct 21, 2007 #2
    For 1kg of water, the energy derived=mgh joules.
    For mega watts, its not 106, but 10^6 watts of power. This is equal to 10^6joules/second.

    Can you work it out now?
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