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Homework Help: Work-Energy Problem

  1. Mar 3, 2016 #1
    1. The problem statement, all variables and given/known data
    A girl is cliff diving. She jumps (assume from rest) from an 80 meter high cliff.

    a) If her mass is 64 kg, and her body can only withstand a force of 11,000 N without breaking a bone, what is the minimum depth she must go into the water and not get hurt?

    b) If we assume she goes 3.8 meters under the water, what force does her body feel?
    2. Relevant equations

    m = 64kg, vf = 0m/s F1 = 11000N, h = 80m, d2 = 3.8m, d1 = ?, F2 = ?
    3. The attempt at a solution
    a) I used the above equation to solve for d2 and I got an answer of 4.65m as the depth.

    b) I used the above equation to solve for F2 and I got an answer of 13,473N as the force.
  2. jcsd
  3. Mar 3, 2016 #2


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    Science Advisor
    Homework Helper
    Gold Member

    That all looks right. But note the question assumes the force is constant in the water. That would not be true in practice.
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