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Projectile Motion -- mountain jumper

  1. Sep 1, 2015 #1
    1. The problem statement, all variables and given/known data
    A jumper runs horizontally off a 910 meter mountain with speed 4.0 m/s and enjoys a free fall until she is 150 meters above the valley floor, at which time she opens her parachute. Ignore air resistance

    2. Relevant equations
    A) how long is the jumper in free fall.

    B) how far from the cliff is the jumper when she opens her parachute?

    3. The attempt at a solution
    My attempt is attached with kinematic equations. I want to use Y to find time.

    I'm confused on Y. Is it the height 910 meters or 910 meters - 150 meters = 760 meters. Can you explain the vertical component to me?

    Attached Files:

  2. jcsd
  3. Sep 1, 2015 #2


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    Homework Helper

    In the case of Y = y_0 + v_0t + 1/2*at^2, your Y at the time you are interested in should be Y at the end of the free fall, or 150m.
    y_0 is the starting height, v_0 is the vertical component of initial velocity (zero) and a should be -9.8m/s^2.
  4. Sep 1, 2015 #3
    Thank you RUber. I am about to rework it.
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