1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Center of force?

  1. Jun 8, 2007 #1
    It's generally common knowledge that gravitational systems have a "center of gravity." Is there such a thing for the other three fundamental forces?

    For example, if one had a number of bar magnets on a tabletop, would there be a "center of electromagnetism?" It seems difficult to picture because of electromagnetic charge. Perhaps it only occurs in special cases? Might there be more than one center?
  2. jcsd
  3. Jun 8, 2007 #2
    The center of gravity is a center of force. It is the balance point between all the mass multiplied by gravity, multiplied by is lever arm. m*g*l.

    The COG can be extended to any system. You just need to use forces in place of gravitational force. In other words, F=mg in this case. So the moment arms are (m*g*l)=(m*g)*l = F*l

    F is any arbitrary force, be it gravitational, electrical, aerodynamic, magnetic.

    Center of electromagnetism is meaningless. electromagnetism is not a force, just a word to describe a phenomenon.

    The center of gravity is called the fist moment (because theres (l)^1,.... get it first-one).

    The second moment is the moment of inertia: m*g*(l)^2 (because theres squared (l)...get it, power of two).
    Last edited: Jun 8, 2007
  4. Jun 8, 2007 #3
    Oh, interesting. I took Adv. Physics in high school and this is the first time I've ever heard of a "moment arm." I'm looking it up and learning a lot. Thank you very much.

    So is there a "color moment" for the strong force or is it more complicated?
  5. Jun 8, 2007 #4
    A moment arm is just a lever arm. Its the between the force and the axis of rotation.

    No such thing as a color moment arm. Light has no mass, it cant cause a moment or a force.
  6. Jun 8, 2007 #5
    Oh, I meant the "color charges" for the strong nuclear force.
  7. Jun 8, 2007 #6
    I dont know what a color charge is, im not a physicist. -sorry.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook