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Homework Help: Question Newton's second Law: F= M * A

  1. Jun 23, 2009 #1

    Why is a in F=m*a
    equal to a =(d^2 x) / (d t )^2 and not to (d x)^2 / (d t )^2

  2. jcsd
  3. Jun 23, 2009 #2

    D H

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    The second derivative is

    [tex]a = \frac {dv}{dt} = \frac{d}{dt}(v) = \frac d {dt} \left( \frac {dx}{dt} \right) = \frac d {dt} \left( \frac {d}{dt} (x)\right)[/tex]

    Note that if we treated this is a fraction (which it isn't), one could write

    [tex]a = \frac {dd}{(dt)(dt)}(x) = \frac {d^2}{(dt)^2}(x)[/tex]
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