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: Work problem in watts

  1. Nov 1, 2006 #1
    not sure how to solve this, having trouble finding the equation I need in my book. any help is appreciated. thanks in advance.

    A 60 kg woman runs up a flight of stairs having a rise of 4.0 m in
    a time of 6.0 s. What
    average power did she supply?
     
  2. jcsd
  3. Nov 1, 2006 #2
    Find the equation for power, and work back from that.
     
  4. Nov 1, 2006 #3
    and another one:

    A horizontal force of 100 N is applied to move a 45 kg cart across
    a 9.0 m level surface.
    What amount of work is done by the 100 N force?


    now with this one do I just do 100 N * 9.0 M = 900 J ? is this correct?
     
  5. Nov 1, 2006 #4
    60kg * 9.8 m/s/s = 588 N
    ok so 588 N * 4 m = 5352 J

    2352/6 s = 392 Watts

    pretty sure thats it. am i right?
     
  6. Nov 1, 2006 #5

    radou

    User Avatar
    Homework Helper

    You're right, except for mixing up the numbers. 588*4 = 2352. :smile:
     
  7. Nov 1, 2006 #6
    yea.. that was a typo. thanks.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook