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I really need help, I don't know how to go about figuring out this problem

  1. Nov 16, 2011 #1
    Tarzan, played by Patrick Huard, 60 kg, must cross a stream
    5 m wide, and full of hungry crocodiles. To do this,
    decides to slide along a sloping tree trunk, hollowed
    and moist so that there is no friction. After the trunk,
    there is a part of 3 m platform covered in mud, with a
    coefficient of kinetic friction of 0.3 leading to the edge of
    stream. It clings so, without jumping to a vine rigid
    8 m with a massless, free to rotate (without friction), in
    lower end which is just below where it is
    attached (the vine hangs). The vine and he traveled an arc
    above the stream. Tarzan must release the vine when
    stops momentarily and land, dry, on the other side of
    stream!
    a) You must ensure that nothing bad will happen to
    Tarzan, and for this you must select the tree trunk to be used (starting height of Tarzan).
    b) The actor who plays the role of Tarzan wants to land on a chair mounted on a spring so as not to injure,
    is stipulated in his contract. This chair is 1 m above the ground and is attached to a spring
    can undergo a maximum compression of 0.3 m. What should be the spring constant of the spring to avoid damage to the actor?
     
  2. jcsd
  3. Nov 16, 2011 #2

    Simon Bridge

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    You have to work out the initial height actor A starts out in order to get him across the river ... as well as the strength of the spring which will catch him.

    You have drawn a picture of the process right?
    That's the first step.

    He'll slide down a slope, then along a 3m horizontal.
    You don't know how long the slope is or the angle of the slope, but you are asked about it'd height ... this is a clue: conservation of energy.

    In fact - that's your approach for the whole thing.
     
  4. Nov 17, 2011 #3
    I got that I had to use conservation of energy but won't I be left with too many unknowns to solve the height?
     
  5. Nov 18, 2011 #4

    Simon Bridge

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    Well walk your way through it.
    You can work out the energy lost on the mud part, and you know how far the vine has to swing.
     
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