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Homework Help: What is your acceleration towards the end of the cliff?

  1. Feb 24, 2010 #1
    You having a mass of 100kg hold one end of an ideal vine (infinitely strong, completely flexible, but having zero mass). The vine runs horizontally to the edge of a cliff, then vertically to where your friend (mass 50kg) is hanging on, above a pack of hungry Velociraptors. A sudden sleet storm has removed all friction, assuming that you can hang on, what is your acceleration towards the end of the cliff?

    Fnet1=Fg1 - Ft
    Fnet2=Fg2 - Fn + Ft

    3. I drew the picture and tried to rearrange equations and use substitution, but had troubles and can't get a reasonable answer. i know 100kg person has Fg2 of 980N down and Fn of 980N up. the 50kg person has a Fg1 of 490N down, but i cant get the Force of tension in the rope (Ft)
  2. jcsd
  3. Feb 24, 2010 #2


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    Re: Forces

    Draw free body diagrams of each person and note the forces acting on each. You have identified correctly the forces on the 50 kg person (his weight down, and unknown tension force up), which is the net force, and which must be equal to 50a.
    For the other person, you need not look in the vertical direction, just consider the forces acting on her in the x direction.. What are they? Then use Newton 2 for that person also. Then continue...
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