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Homework Help: Gravitational potential energy of skier

  1. Feb 23, 2008 #1
    1. The problem statement, all variables and given/known data

    A 78.9-kg skier rides a 3150-m-long lift to the top of a mountain. The lift makes an angle of 11.9 ° with the horizontal. What is the change in the skier's gravitational potential energy?

    2. Relevant equations


    3. The attempt at a solution


    I am confused if the angle i used was correct or should i subtract it from 90 or something. I tried that and it was still wrong. Can someone tell me what im doing wrong? is the angle used right
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 23, 2008 #2


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    First of all, the skier is going UP the mountain. Should his gravitational potential increase or decrease?
  4. Feb 23, 2008 #3
    Another note, although they are the same units, you are looking for gravitational potential energy, not work, so your formula isn't quite right.

    GPE = mgh

    So, you need to find 'h'. If the angle is 11.9˚ with the horizontal, how would you find the height?
  5. Feb 23, 2008 #4
    oh, so the height would be 3150*sin11.9= 649.54m

    GPE= 78.9*9.8*649.54=502,237.3J

    Is that right?
  6. Feb 23, 2008 #5
    Assuming the skier started at height 0, then that answer looks right to me.
  7. Feb 23, 2008 #6
    that was correct..thanx!
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