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Homework Help: Angular acceleration of a Propeller

  1. Mar 4, 2008 #1
    [SOLVED] angular acceleration of a Propeller

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

    An airplane propeller is rotating at 2000rev/min .

    [tex]\omega[/tex]z = 209rad/s

    How long in seconds does it take for the propeller to turn through 40degrees?

    2. Relevant equations

    [tex]\theta[/tex] = 1/2[tex]\omega[/tex]t

    [tex]\omega[/tex]z = d[tex]\theta[/tex]/dt

    3. The attempt at a solution

    40degrees = (2[tex]\Pi[/tex]/360degrees) = .698rad

    209rad/s = .698rad/t

    209rad/s(t) = .698rad

    t = .698rad/209rad/s

    t = .0033s wrong

    I'm sure I'm using the right equations, does anyone know what I'm doing wrong?

    any help is appreicated, I think I'm missing something obvious just not sure what it is.
  2. jcsd
  3. Mar 4, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks OK to me. Why do you think it's wrong?
  4. Mar 4, 2008 #3
    masteringphysics told me it was wrong
  5. Mar 4, 2008 #4
    oh for the love of God, I entered .003 instead of .0033 and they counted it wrong, I hate masteringphysics, thanks for checking anyway Doc Al
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