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Help with a couple physics problems

  1. Nov 12, 2006 #1
    I am having some trouble with a couple of physics h/w problems and would appreciate any help you can give me..

    Julie pulls a 61.5 N bag a distance of 278 m at a constant velocity. The force she exerts is 48.4 N at an angle of 66.8 degrees above the horizontal.
    I found the work julie does on the bag to be 5300 J.
    Yet I am not sure how to find A) the work done by the force of friction on the bag and B) the coefficient of kinetic friction on the bag

    Next problem is
    A rain cloud contains 2.82 x 10^7 kg of water vapor.
    The acceleration of gravity is 9.81m/s^2
    How long would it take a 2.10 kW pump to raise the same amount of water to the cloud's altitude of 1.44km? Answer in seconds (s)
    [I tried Power= work(FsCOS[theta]) divided by t. So 2100w=2.82x10^7(9.81)1440m COS 90 degrees DIVIDED by t, which just equals 0 since cos90 is 0. I DONT GET IT!]
  2. jcsd
  3. Nov 12, 2006 #2
    why is theta 90? why is this not in the Homework forum?
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