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Newton's 2nd Law/Forces

  1. Sep 12, 2007 #1
    1. The problem statement, all variables and given/known data
    A 50 kg diver enters the water moving at 4 m/s. He eventually comes to a stop 3 meters below the water surface. What amount force brought the diver to a stop?

    2. Relevant equations
    Is the acceleration -9.8 m/s^2?
    Then, would you use F = ma to find the net force?

    3. The attempt at a solution
    i tried to do F = (50 kg)(-9.8 m/s^2) but i don't think that's right...

    Thank you.
  2. jcsd
  3. Sep 12, 2007 #2
    This will not work as the acc is not equal to -g. You have the velocity when the body touches the water surface. This is the initial velocity. Now the final velocity is zero.And the distance is 3m. So by v^2-u^2=2ad.You can find a, and then you can apply f=ma.Here v is the final velocity and u is the initial velocity.
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