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Homework Help: Grandfather clock torque homework

  1. Dec 3, 2009 #1
    1. The problem statement, all variables and given/known data
    A 55 g mouse runs out to the end of the 17cm long hand of an old grandfather clock when the clock reads 10min past the hour. What torque does the mouse exert about the rotation axis of the clock hand.

    2. Relevant equations


    3. The attempt at a solution

    The force acting on the mouse is his weight, so F=mg which turns out to be .55N. The radius, in meters, is .17m. Here's the tricky part, theta describes the angle between the force and the radius, so, if it is 10 past the hour, the long hand is making a 30 degree angle with the x axis (or the 3 on a clock). The force, long hand, and x axis make a 90 degree angle so if the angle the long hand makes with the axis is 30 degrees and the angle force makes with the axis is 90 degrees then theta must equal 60 degrees.

    That is my logic but I am not sure how sound it is. If anyone can help confirm or deny this it would be much appreciated!
  2. jcsd
  3. Dec 3, 2009 #2


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    Homework Helper

    Re: Torque

    Yup, your reasoning is sound.
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