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Working out speed without time

  1. Oct 24, 2012 #1
    If a man who weighs 1000Newtons(N) makes a bungee jump off a bridge with a 6m bungee rope, this rope has a elastic constant of 2000N/m

    A) what is the fastest speed he reaches
    B)what is his maximuum kinectic energy
    C)how far will bungee rope extend until energy is transformed to elastic potential energy



    2. Relevant equations
    F=ma, F=kx E=1/2*k*x^2 these are all i know



    3. G= 9.81m^2 Gravity*weight/2000 sorry IDK guys please help GCSE Science
     
  2. jcsd
  3. Oct 24, 2012 #2
    Are you familiar with potential and kinetic energy?
     
  4. Oct 24, 2012 #3
    yes i m thanks for replying
     
  5. Oct 24, 2012 #4
    Could you divide this jump in phases? What energy do you have at the bridge, what energy do you have before the "rope" starts stretching?
     
  6. Oct 25, 2012 #5
    Check your question values. That bungee rope looks rather stiff. You might have picked up an extra zero.
     
  7. Oct 25, 2012 #6
    Thanks for trying to help me guys appreciate i ve got the answer now
    first 1/2*m*v^2 = mgh
    then pug in the values
     
  8. Oct 26, 2012 #7
    Hello, John.

    Your equation above would work for a situation before rope starts stretching.

    You have a 3 key situations: before jump (potential energy is max), before stretching of the rope (kinetic energy is max) and after stretching ("spring" energy).

    Please look into photos I attached.
     

    Attached Files:

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