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Homework Help: Geometric Progression

  1. Jun 8, 2009 #1
    1. The problem statement, all variables and given/known data
    A ball is dropped vertically from height h onto a flat surface, after the nth bounce it returns to high h / 3^n. Find the total distance travelled by the ball.

    2. Relevant equations

    Sum (infinity) = [tex]\frac{a}{1 - r}[/tex]

    3. The attempt at a solution

    I don't see the problem,

    r is 1/3, a is h,

    [tex]\frac{h}{ 2/3 }[/tex]= 1.5h, however the problem is i'm told the answer is 2h.

    Any help would be appreciated
  2. jcsd
  3. Jun 8, 2009 #2


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    Science Advisor
    Homework Helper

    If it bounces to height h/3^n, it will also have to drop to the ground from height h/3^n again. So it always travels this distance twice, except when n = 0.
  4. Jun 8, 2009 #3
    Gotcha, thank you.
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