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Homework Help: Human Falling Determine Force on Achilles

  1. Sep 6, 2011 #1
    1. The problem statement, all variables and given/known data
    A 45 kg woman jumps from a height of 2.5 meters to a solid
    floor. In an attempt to minimize the likelihood of injury, she lands on the ball
    of her feet (the pads just behind her toes) with her knees bent. What
    average force is needed on her feet to stop her fall if her center-of-gravity
    after touching the floor drops 80 cm before she stops? If the horizontal
    distance from the ball of her foot to her talus (where her tibia exerts its
    force) is 15 cm, and from talus back to the Achilles tendon is 3.6 cm, what
    average force does the Achilles tendon suff er during the stopping time

    2. Relevant equations
    F = ma
    vf^2 = vi^2 + 2ad

    3. The attempt at a solution

    I've solved for vf = 7 m/s and the average deceleration of the woman (49/(2*.8m)) = 30.625 and even got to an average force answer of 6028.13 newtons per second using average deceleration and time but just got stuck from there. Can anybody help me out?
  2. jcsd
  3. Sep 6, 2011 #2
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