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Homework Help: Newton's 2nd

  1. Sep 27, 2010 #1
    A woman raises herself in a bucket. How hard must she pull downward to raise herself slowly at constant speed? The mass of the person plus the bucket is 79 kg.

    m=79kg
    g=9.8m/s^2 (downward)

    i know [tex]\Sigma[/tex]F=ma so i end up with 774.2 N. i'm a little lost as where to go now.
     
  2. jcsd
  3. Sep 28, 2010 #2
    Sum the forces in the y direction, if speed is constant that acceleration is zero

    Forces in y =Fp- Fg = 0

    Solve for fp
     
  4. Sep 28, 2010 #3
    You actually already solved it. For something to move at a constant speed, the net force has to be 0. So she just has to pull hard enough to overcome the gravitational force. Which you already calculated.
     
  5. Sep 28, 2010 #4

    Doc Al

    User Avatar

    Staff: Mentor

    You need to understand how she is raising herself. A simple rope and pulley arrangement? A diagram would be helpful.
     
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