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Homework Help: Short force pulley problem

  1. Oct 3, 2008 #1
    A 20 kg monkey holds on to a rope that passes over a frictionless pulley and is attached to a 20 kg bunch of bananas. The monkey starts to climb the rope to get the bananas.
    a. as the money climbs, do the bananas move up, down, or remain at rest?
    b. as the money climbs does the distance between the money and bananas increase, decrease, or remain the same?
    c. the monkey lets go of the rope. before reaching the ground he grabs the rope to stop his fall. what do the bananas do?

    a:remain at rest
    b:remain the same
    c:the bananas fall. then rise, then descend to the same level as the monkey

    I think those are the answers, but I'm not sure why. thanks for any help!
  2. jcsd
  3. Oct 3, 2008 #2
    (a) think of it this way, initially the system is in equilibrium so there is the force of mg in the negative y direction on either side of the pulley.
    When the monkey starts to climb he accelerates . Think of the connection between acceleration and force.

    (b) This depends almost directly to your answer of question (a). Ie. if as he climbs the bananas move up at the same rate, then the distance remains the same.
    explain your reasoning for this question please

    (c) Why do the bananas rise? Remember the monkey and the bananas have the same mass, when they fall they fall at the same rate.
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