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What is a centrifugal force?

  1. Mar 12, 2008 #1
    What is a centrifugal force? Is it a pseudo force?

    Does it really exist?.. Maybe i am not getting the idea of what a pseudo force is...
  2. jcsd
  3. Mar 12, 2008 #2
    The centrifugal force is an outward-directed inertial force exerted on a body when it moves azimuthally in a noninertial rotating reference frame.
    Some scientists use that term to refer to inertial forces. However this is not universally used since some scientists consider inertial forces to be real (whatever that means).
    Can't say unless you first tell us what you mean by "real"? As Ray D'Inverno wrote in his GR text The status of inertial forces is again a controversial one. In my opinion is is quite real. A good example is the following


    For other examples of physicists with the same opinion consider the following:

    From Newtonian Mechanics, A.P. French, The M.I.T. Introductory Physics Series, W.W. Norton Pub. , (1971) , page 499. After describing the inertial force as seen from an accelerating frame of reference French writes
    From The Variational Principles of Mechanics - 4th Ed., Cornelius Lanczos, Dover Pub., page 98.
    From Cosmological Physics, John A. Peacock, Cambridge University Press, (1999), page 6-7
    Does this help?

  4. Mar 12, 2008 #3


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  5. Mar 12, 2008 #4
    I sometimes find it helpful to think first about the inertial force we've all experienced in an accelerating vehicle. We're certainly pushed back into the seat (or thrown forward under deceleration), so the force feels "real" enough. What is missing, however, is any kind of field that exerts this force, much less a source for such a field. This distinguishes such forces from ones like electrical or magnetic forces (or gravitational forces, at least when understood as Newton did), where there are fields with sources.

    The Equivalence Principle definitely makes the question more interesting, and I can't say that I've ever really felt I had a complete handle on it. I'm incapable of riding a subway without wondering how the forces I feel as I get jerked around are somehow equivalent to gravitational forces.
  6. Mar 12, 2008 #5


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    it's a pseudoforce that appears in an accelerated frame of reference that, within that frame of reference of curved or circular motion, appears to pull objects away from the center of rotation.

    the real force is the centripetal force that is pushing the objects in circular motion toward the center of rotation. so, if you're in a car going around a bend in the road, it's not that you're being pulled outward and pressing against the car door (despite what you think you feel) but that the car door is pushing you in the direction you are being accelerated (which, in circular motion, is toward the center of rotation).
  7. Mar 12, 2008 #6


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    Centripetal force is the force that accelerates a moving body "inwards", and centrifual force is the equal and opposite reaction force to the acceleration caused by the centripital force.
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