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Homework Help: Problem encountered

  1. Oct 9, 2006 #1
    I am not even sure where to start with this question. I believe I need to incorporate this equation into this problem, but not too sure.


    A 16.0-kg monkey hangs from a cord suspended from the ceiling of an elevator. The cord can withstand a tension of 200 N and breaks as the elevator acclerates. What is the elevator's minimum acceleration(magnitude and direction)?

    Thanks for any help
  2. jcsd
  3. Oct 9, 2006 #2


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    The monkey and rope are attached to the elevator, so they accelerate at the same rate of the elevartor until the rope breaks. Examine the forces acting on the monkey. A tension of 200 N up. A weight of mg acting down. Use Newtons 2nd law to solve for a. Your equation is correct except use T instead of w on the left side. Is that what you meant?
  4. Oct 9, 2006 #3
    It always helps to draw out a schematic of the system. Draw the monkey and then the forces in each directions and that will help a lot in an problem dealing with summing the forces (newton's 2nd law).
  5. Oct 9, 2006 #4
    How do I solve for the magnitude and direction?
  6. Oct 9, 2006 #5
    a= 12.5 m/s^2

    The monkey would be moving up since he is not "weightless"

    Is this correct?
  7. Oct 9, 2006 #6


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    You must draw the free body diagram of the monkey. The rope is pulling up on it with a force of 200N. Gravity is pulling down on it with a force of
    mg= 16(10) = 160N. The NET force is therefore (200-160) = 40N upward.
    From Newton's 2nd law, the NET unbalanced force acting on the monkey produces an acceleration in the direction of that force
    F_net = ma
    This is the minimum acceleration of the monkey.
    It is also the minimum acceleration of the elevator.
    magnitude is 2.5m/s/s
    direction is UP (which you answered correctly).
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