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Acceleration and free fall problem

  1. Oct 22, 2009 #1
    1. The problem statement, all variables and given/known data
    Rachel drops straight off a high dive whose board is 5 meters above the surface of the water. How long does it take Rachel to hit the surface of the water? How fast is Rachel traveling when she hits the surface of the water?


    2. Relevant equations



    3. The attempt at a solution
    I made an x vs. t graph, a v vs. t graph, and an a vs. t graph.
    My variable list is as follows:

    x at time 0(initial location)=5m
    x(location) at end time=0m
    initial velocity= is unknown
    Velocity at end=0m/s
    time=is unknown
    acceleration=-9.8m/s^2 (which is free fall)
     
  2. jcsd
  3. Oct 22, 2009 #2
    The graphs, although conceptual, do little to help you get into the meat of the equations. Review your core kinematics equations, and choose which ones contain the variables you need to solve for.

    Also, her initial velocity is zero (she starts from rest, and drops straight down). Her velocity the moment before she hits the water is the one you want to solve for.
     
  4. Oct 25, 2009 #3
    Would my answers to these questions for this problem be correct:
    How long does it take Rachel to hit the surface of the water?
    1.10 sec

    How fast is Rachel traveling when she hits the surface of the water?
    -9.9m/s
     
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