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Is the centrifugal force fictitious or just incidental? 
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#1
Dec2803, 10:21 PM

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Is the "centrifugal force" fictitious or just incidental?



#2
Dec2803, 11:30 PM

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The cetrifugal force is part of accounting for an accelerated frame of reference. It corresponds to being in a reference frame that is accelerated.
I'm not sure what you mean by ficticious or incidental.e 


#3
Dec2803, 11:33 PM

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#4
Dec2803, 11:43 PM

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Is the centrifugal force fictitious or just incidental?
I never cared for that term because it causes a lot of confusion. 


#5
Dec2903, 07:33 AM

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In fact in Lagrangian dynamics there is nothing which requires an inertial frame. Lagrangian dynamics is based on the Hamilton's Principle (Principle of extremal action) which does not depend on the frame of referance chosen. 


#6
Dec2903, 01:34 PM

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I remember looking at a study done by students at the University of Michigan that said either centrifical or centrifigal force doesn't exist. Can someone clear that up?



#7
Dec2903, 01:41 PM

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#8
Dec2903, 02:19 PM

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#9
Dec3003, 04:54 PM

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I would say that the centrifugal force, as well as the centripital force, are clearly incidental. That is, these are forces that cannot be created independent of one another, therefore they are incidental unto each other.



#10
Dec3003, 05:58 PM

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For example: Suppose in your living room there is a uniform gravitational field. Suppose also that there is an electric field in your living room which is in the direction pointing from the floor to the ceiling. Place a ball which is charged such that it floats. I.e. the gravitational force is equal and opposite to the electric force. Then the force on the charge due to the gravitational field is an inertial force. The force on the charge due to the electric field is not an inertial force. 


#11
Dec3003, 07:40 PM

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Are all noninertial forces nongravitational (i. e., exclusively electromagnetic, strong or weak)?



#12
Dec3003, 07:53 PM

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To go in a circle something must supply the centripetal force or you go in straight line. That centripetal force on the body is a real force and by Newton's 3rd law has a reaction force. If a string pulls on a weight to make it go in a circle then the weight pulls on the string. Real forces. Now analyze the weight's motion in the rotating reference frame. The weight is not accelerating in this frame and so there is no centripetal acceleration. Yet the string still pulls on the weight. Why doesn't the weight move inward? To explain why, the centrifugal force is 'invented' to make the net force on the weight zero in the accelerated reference frame. But nothing is really pulling the weight inward. In that sense it is a 'fictious' force. The 'proof' is that when you let go of the string the weight flies off tangentially, not radially. All that said, I agree that 'fictious force' is a bad term that creates more confusion. 


#13
Dec3003, 11:57 PM

P: 687

I understand the force of the electric field is not inertial. I also understand that the force I exert on the floor is inertial. What do you call the force that the floor exerts on me? Let me put it this way: 2 spheres (A and B) of equal mass, say 10 kg, with no other forces affecting them except their own gravity, are separated by 1 m. Naturally, they are attracted to each other. The force that each sphere exerts on each other due to gravitation is inertial. At the instant they come in contact from the perspective of sphere A, sphere A exerts an inertial force against sphere B. Sphere B exerts an equal and opposite force on sphere A. What is that force that B exerts on A? I promise I'm not trying to debate what you said. I really don't understand. 


#14
Dec3103, 05:43 AM

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#15
Dec3103, 05:46 AM

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There are contact forces between two bodies which are better explained through solid state physics and you've just described the contact forces. However I gave the electric force so as to simplify the description. Instead of thinking in terms of solid spheres think of charged bodies. Take two identical bodies, i.e. they have identical mass and identical charge, and place them at a distance from each other such that the electric force exactly balances the gravitational force. Then apply the explanation I gave above. 


#16
Dec3103, 02:09 PM

P: 687

Thanks Arcon, I understand what you are saying.



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