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Homework Help: Formula of power

  1. Jul 31, 2016 #1
    1. The problem statement, all variables and given/known data
    i was told that Power = torque x (angular velocity)

    2. Relevant equations

    3. The attempt at a solution
    I found that power has unit of Nm/s,
    torque x (angular velocity) has unit of Nm(rad/s), is the formula given wrong?
  2. jcsd
  3. Jul 31, 2016 #2


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    Angles do not have a dimension in the way that mass, time, etc. do.
    Consider e.g. that a circular arc of radius r and angle θ has length rθ.
    Nevertheless, they do have units, and the unit "radian" is chosen in such a way that you do not need to include a constant in the rθ formula. It turns out that this also means you do not need a constant in the power formula if radians are used in the angular velocity.
  4. Aug 4, 2016 #3

    rude man

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    Or, angles are dimensionless.
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