Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help with power problem

  1. Jan 12, 2008 #1
    1. The problem statement, all variables and given/known data

    water flows over a section of niagara falls at the rate of 1.2*10^6 kg/s (kilograms per second) and falls 50.0 m (meters). How much power is generated by the falling water?

    2. Relevant equations


    3. The attempt at a solution

    gravitational potential energy (PE grav)=mgh (mass*gravity*height)
    PE grav=(1.2*10^9 g/s)(9.81)(50.0 m)
    PE grav=588,600,000,000

    but PE is measured in joules. and power is measured in watts. so how do i get from PE to W?
    Last edited: Jan 12, 2008
  2. jcsd
  3. Jan 12, 2008 #2
    1 Watt = 1 Joule per second
  4. Jan 12, 2008 #3


    User Avatar
    Homework Helper

    You were given the rate in the question. Look at the units in your calculation.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook