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Homework Help: Last one I PROMISE! gravity question

  1. Jun 18, 2007 #1
    1. The problem statement, all variables and given/known data

    A rock of mass 32 kg accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 242 N. What is the magnitude of the acceleration of the rock?

    2. Relevant equations

    F=ma (?)

    3. The attempt at a solution

    I just did 242 N/32 kg and thought that was good but apparently that's not right?
  2. jcsd
  3. Jun 18, 2007 #2


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    The SUM of all forces is: F = ma

    so you find the force acting on the rock directed down wards, and upwards; the you will get the sum of the force acting on the rock.
  4. Jun 18, 2007 #3


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    There is a downward force of mg and an upward force of 242 N.
  5. Jun 18, 2007 #4
    that's what i thought of later too, but how much force does gravity exert in N?
  6. Jun 18, 2007 #5
    OK, I got the answer.
    Thank you.
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