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How to calculate the height of a skier

  1. May 23, 2016 #1
    1. The problem statement, all variables and given/known data
    I want to calculate the height h of the skier in this figure
    upload_2016-5-23_16-6-52.png

    2. Relevant equations
    potential energy and kinetic energy and there is no friction

    3. The attempt at a solution

    mgh = 0,5 *m*v^2
    v=√ (2*g*h)

    Now calculate the h when he goes up

    mgh= 0,5 *m*√ (2*g*h)^2


    Am I doing right ?

    Thanks



     
  2. jcsd
  3. May 23, 2016 #2
    What you got is an identity. You need more information of the person on the top of the hill to get his condition, such as velocity~
     
  4. May 23, 2016 #3
    mgh = 0,5 *m*v^2
    v=√ (2*g*h)

    This is right but after this, only calculate with its vertical component (v*sin(28 deg)), when calculating h.
     
  5. May 23, 2016 #4
    These informations are enough, you dont need more!
     
  6. May 23, 2016 #5
    You only got an identity, because you didnt calculate with the right component of speed.
     
  7. May 23, 2016 #6
    thank you all
     
  8. May 24, 2016 #7

    haruspex

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    You need to be careful with 'h'. There is a specific height in the problem which is labelled h, and there is the generic h in the equation gh=v2/2. Don't get them mixed up.
    First, find the velocity at the launch point.
     
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