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Homework Help: Physics-momentum qs!

  1. Mar 25, 2010 #1
    1. The problem statement, all variables and given/known data
    Divers at Acapulco, Mexico, regularly dive head first from a heigh of 36m into water 3.6m deep. [assuming g=9.8m/s^2) and that air resistance is negligible.]
    a) What would be the vertical momentum of a 50kg diver when he reached the water?
    b)If he lost his vertial velocity by the time he reached a depth of 3.0, what average force must the water exert on him?
    c)Comment on the likely results if the inital force as he entered the water was ten times the averag force.
    d)The rocks at the base of the cliff jut more than 6m out into the water. If a diver hit these would he be killed. Why?

    *****need help with c) and d)

    2. Relevant equations
    Ft=m(change in v)

    3. The attempt at a solution
    honestly, I have no idea...if his inital force was 10X the average force...does this mean he hits the water will 10x the force that the water pushes back up on him...so, he travels downward more...it takes more time for his velocity to come to a rest...so therefore, the average force has less of an impact on him....for d)...he will be killed if he hits the rocks b/c since they are hard&have less SA than the water, he will be in contact with them for less time...so there will be a greater average force exerted on him and he is killed...
  2. jcsd
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