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Homework Help: Torque on a block with acceleration 4i-3j.

  1. Apr 7, 2007 #1
    1. The problem statement, all variables and given/known data
    A 2.0-kg block starts from rest on the positive x axis 3.0 m from the origina and thereafter has an acceleration given by a = 4i-3j. The torque, relative to the origin acting on it at the end of 2.0 s is:

    2. Relevant equations

    linear acceleration= (radius)(angular acceleration)

    torque= (moment of Inertia)(angular acceleration)

    3. The attempt at a solution

    I found the angular acceleration using the formula above
    moment of Inertia=(mass)(radius square)
    Then find the torque using the formula above

    that's not it....help!...:frown:
  2. jcsd
  3. Apr 7, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    HINT: Definition of torque;

    [tex]\tau = \vec{F}\times \vec{r} = m\vec{a}\times\vec{r}[/tex]
  4. Apr 7, 2007 #3

    Doc Al

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    Staff: Mentor

    Hint: Where is the block at the end of 2 seconds?
  5. Apr 7, 2007 #4
    thanks for the help guys...
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