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Moment of force

  1. Aug 19, 2005 #1
    This question may sound silly to all of you brainy guys out there but I am one silly guy.
    While calculating the moment of a force how do you choose which component (horizontal or vertical) to choose? I know that M=F*d. Its confusing when authors sometimes use the veritical and sometimes the other component.
    Also please let me know if there is a nice little websites where such basic conepts could be found.
  2. jcsd
  3. Aug 19, 2005 #2


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    Science Advisor

    The component you need is whatever component is perpendicular to the radius you are using as the distance. For example, imagine a circle. If you draw a radius from the center to the 3 o'clock position, then the vertical component will produce the torque. If you draw a radius from the center to the 6 o'clock position, then it would be the horizontal component. The radius dictates the component used.

    When in doubt, hyper physics is a great website:
  4. Aug 20, 2005 #3
    inother words you would use the distance that is shortest that makes a rright angle from the line of action to the position of application
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