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Homework Help: Gravitational potential energy

  1. Oct 12, 2004 #1
    A 70.0 kg skier rides a 2860 m long lift to the top of a mountain. The lift makes an angle of 14.8° with the horizontal. What is the change in the skier's gravitational potential energy?

    What equation would I use to solve this problem?
     
  2. jcsd
  3. Oct 12, 2004 #2
    First of all since the lift is an inclined plane, there is a horizontal and vertical component when 2860 is the hypothenuse

    find the vertical component

    vertical component is now the dH is dU = MG dH
     
    Last edited: Oct 12, 2004
  4. Oct 12, 2004 #3
    i don't understand what you are saying. What is dU and dH?
     
  5. Oct 12, 2004 #4
    dU = the change in gravitational potential energy

    dH = the change in height

    Because

    dU = mgh2 = mgh1 = mg (h2 - h1) = mg dH
     
  6. Oct 12, 2004 #5

    Pyrrhus

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    Remember the trajectory doesn't matter for the gravity potential energy, only the change of height.
     
  7. Oct 13, 2004 #6
    You know the mass, the unknown is the height.

    If the hypotenuse of a triangle is 2860 meters long and the angle is 14.8 degrees what is h?

    Then mass x height = potential energy.

    :)

    Kirk
     
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