#1
Jul1303, 10:15 PM

P: n/a

can someone please compare and contrast the phenomenon of the centripetal force versus the centrifugal force.




#2
Jul1303, 11:01 PM

Emeritus
Sci Advisor
PF Gold
P: 2,352

Centrifugal means " to flee the center" and Centripetal means "to seek the center" They are just terms used to decribe whether any given force acts towards or away from a center. 



#3
Jul1403, 06:44 PM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 38,879

Imagine swinging a rock on a rope. A moving object tends to move in a straight line. In order to make the rock move out of a straight line into a circle, you have to keep pulling on the rope: that "cetripetal" force.
Of course, you hand feels the rope pulling back on it ("equal and opposite reaction"). That's "centrifugal" force. Centripetal force is always directed toward the center of the curve, centrifugal force is always directed away from the center. 



#4
Jul1403, 09:00 PM

P: 203

centripetal versus centrifugal
Centrifugal force is a "fictitious force", hence it is not really a force.
Imagine if a person is on a Merrygoaround spinning. He would feel a "force" that is pulling him away from the Merrygoaround, therefore he has to hold on to the bar on the Merrygoaround enable to stay on, the force that he is exerting on the bar is acting directly inwards with respects to the center of the Merrygoaround, and this force is what we called a "centripetal force". Now imagine the person releases his grip on the bar, and got pull off by this "mysterious force" off the Merrygoaround. An observer that is on the same Merrygoaround, would see that the person is flying "radially" away from the Merrygoaround. But if there is an observer on the ground in a stationary reference frame, he would see this rather differently, he would see the person instead of flying radially, he would see him flying away from the Merrygoaround "tangetially". People who have done physics knows that the veloctiy vector is always at right angle to the centripetal force, we can therefore say, from the viewpoint of the observer in a staionary nonrotational reference frame that the person is really flying away from the Merrygoaround due to his inertia, because inertia is the resistance of change in motion, in this case, the person's inertia has overcame the centripetal force, and thereby he will fly tangetially away from the Merrygoaround. The reason that centrifugal force is called a fictitious force is because that it only agrees with the definition of a force (a push or a pull) when the observer is in the same rotating reference frame as the obejct; while an observer in an nonrotational stationary reference frame does not need to be equiped with the concept of centrifugal force. The existnce of centrifugal force is really a matter of fact that which frame of reference that the observers are in. 



#5
Jul1603, 03:10 PM

P: 228

Hyperreality beat me to it, but there is no centrifugal force.
That force is really the tangential velocity "pushing" an object away from the center. Just some repetitive info. 


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