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Homework Help: Free-fall problem

  1. Jun 6, 2006 #1
    I've spent about an hour and a half on this question, working with different formulas and manipulating equations but I still can't figure it out. The question:

    "A ball, dropped from rest, covers three-quarters of the distance to the ground in the last second of its fall. From what height was the ball dropped, and what was the total time of the fall?"

    I would type here what I have figured out, but really it seems like I have gotten nowhere. I think I've come close, though.
    Last edited: Jun 6, 2006
  2. jcsd
  3. Jun 6, 2006 #2


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    Why don't you tell us what your thinking is on the problem and give some indication of what you have tried.
  4. Jun 7, 2006 #3

    Andrew Mason

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    Work out the expression for total height in terms of total time.

    Then work out how much distance is fallen in t-1. That will give you another expression for h. Can you take it from there?

    Last edited: Jun 7, 2006
  5. Jun 8, 2006 #4
    Convert what you said into an equatiom, think about distance=rate*time, and you will need to use that from free-fall the velocity of the ball at any time t is v=at, where a=9.8 m/s^2.
  6. Jun 8, 2006 #5


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    It is not nesscary to find the velocity at any point during the free fall. The problem can be solved with the application of a single kinematic equation.
    Last edited: Jun 8, 2006
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