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Simple Torque Question

  1. Apr 2, 2010 #1
    There is no answer in the back of the textbook to the problem I did. I'm self-studying, so can someone check if my answer is correct.

    1. The problem statement, all variables and given/known data
    The forearm accelerates a 3.6 kg ball at 7.0 m/s2 by means of the triceps muscle. The forearm is 30 cm long and is perpendicular triceps muscle. Calculate the torque and the force exerted by triceps muscles.

    2. Relevant equations

    [tex]\tau[/tex] = I[tex]\alpha[/tex]

    [tex]\tau[/tex] = R x F

    3. The attempt at a solution

    a = 7.0 (m/s2), m = 3.6 (kg), r = .03 (m)
    [tex]\tau[/tex] = I[tex]\alpha[/tex] , [tex]\alpha[/tex] = a/r, I = m*r2
    = m*r2[tex]\alpha[/tex]
    = m*r*a
    = 3.6*.03*7
    [tex]\tau[/tex] = .756

    [tex]\tau[/tex] = r * F
    F = [tex]\tau[/tex]/r
    F = .756/.03
    F = 25.2

    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 3, 2010 #2


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    Homework Helper

    Your answers are correct. Though you could have found the force (ma) first and then the torque (rF)
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