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Homework Help: Free Fall Question

  1. Jan 25, 2014 #1
    1. The problem statement, all variables and given/known data

    In the final second of its free fall, an object covers half the height of its total fall. From what height did it fall?

    2. The attempt at a solution

    I know that the velocity and acceleration at the final second must be enough for the object to cover half the height.

    Distance traveled due to acceleration:

    = (0.5)(9.81)(1^2) = 4.905 meters.

    I understand that whatever the velocity is, it must be enough for the object to travel (h/2) - 4.905 meters. H being the total height.

    However, this is where I am having trouble.
  2. jcsd
  3. Jan 25, 2014 #2


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    it might make most sense to use fall time as the variable. if the total fall time was 2 seconds, how far would it have gone ... in the first sec, and in the second sec?
    .... is that half-way ?
    ok, what if the total time was 3s? how far in the 1st part (2 s) , compared to the 2nd part (1s)?
  4. Jan 25, 2014 #3
    So, it is basically trial and error?
  5. Jan 25, 2014 #4
    no on the contrary you should try it by taking time as a variable.
  6. Jan 25, 2014 #5


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    you can do it algebraically, if you know what expressions to equate.
    If you do a couple of particular examples, you will find out (ie, learn) what those expressions ought to be.
    Try it! (I'm not sure you are using the entire distance formula)
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