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Homework Help: A GM1m2/r2 question

  1. Oct 11, 2005 #1
    Pelle who weights 68 kilos, cycles up a steep hill. He stands up and pushes all his weight on the pedals. Pedals moves in a circle with the radie 18cm. Which is the biggest momentum he can affect the pedals with

    Well my answer is wrong but this is how I did
    Because I don't know the answer I take

    m2= 9,82*(0,18)^2 = 0,318168/6,67*10^-11 = 4770134933
    Which is the second mass

    M1 = His weight 68kg

    Then I take 68*4770134933 =3,24691754^10*-11 * 6,67*10^11 = 21,635424
    and then I finely dived it which is 21,635424/0,18^2 = 667,76 N

    I get but it's not right answer should be 120Nm please help me !:surprised :surprised :surprised :surprised :surprised
  2. jcsd
  3. Oct 11, 2005 #2


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    Homework Helper

    The unit of moment of a force (often called torque) is Nm, and the equation:
    [tex]\mathbf{M} = \mathbf{r} \times \mathbf{F}[/tex]

    This problem has little to do with gravitation.
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