Originally Posted By: cdmohatta
Centrifugal force comes because of rotating motion.
Doesn't the earth rotate?
OK, some grade-school physics here.
Centrifugal force (a force pushing outward from a rotating object) is an illusion. It does not exist. It is an expression of inertia.
What does exist is centripetal force, that is a force that pushes inwards towards the center. Inertia is the tendency for a moving object to continue moving in a straight line. Centripetal force exerted through a medium such as a car seat, or the bottom of a bucket, alters your motion from a striaght line to a curve. This force pressing on you is the equvalent feeling of you pressing on it, thus the illusion of "centrifugal" force.
Now in the case of the earth, there is no appreciable centripetal force, since there isn't a good medium to transfer it. Thus you will weigh
less on a rotating earth than one that is standing still, and you will weigh less at the equator than at one of the poles.