Is "support force" a "true force"? it seems incompatibe with F=ma

WannabeNewton

Quote by stevendaryl

The distinction, as I understand it, in the case of a mass swirling on a string, is that "centrifugal force" is a fictitious force, and acts on the mass, while "reactive centrifugal force" is a real force, and acts on the string. They are numerically equal, but they act on different objects.

Hmm, can't say I've ever heard of the "reactive centrifugal force". I'll read up on it thanks.

EDIT: I tried looking it up and I just found other forum links, a wiki link, and a facebook link (lol). Is there like some textbook this is discussed in? I couldn't find anything in Kleppner about it, which is the book I usually turn to, nor could I find anything in Taylor.

MrAnchovy

Quote by AlephZero

On the other hand I have never (in 30 years in industry) heard anybody use the term "reactive centrifugal force", until a few recent threads in PF - and I don't see any merit in it.

I agree; I had never heard it before until used here and I will stop using it (even reluctantly and in brackets) now.

Quote by AlephZero

FWIW I spend a lot of my working life on the dynamics of rotating machines. I can live with the term "centrifugal force" though I prefer "centrifugal stress" which is both a real stress and self explanatory - i.e. the stress fiield caused by the rotation of the system.

I can see some merit in "centrifugal stress" - but only if we replace "normal force" with "normal stress" too! And if we are going to stop using the word "force" for things that are forces, we should definately stop using it for things that are not - so "centrifugal effect" is a much better term to be used in a rotating reference frame.

On a more serious note, what WOULD be better would be if those who have mastered the maths of non-inertial frames of reference (or think they have) did not proclaim with such puffed-up joy statements such as "centrifugal force doesn't exist" which causes confusion and doubt in minds that are beginning to relate equations of motion to their everyday experience - this is exactly what turns intelligent, curious people away from science.

Emilyjoint

On a more serious note, what WOULD be better would be if those who have mastered the maths of non-inertial frames of reference (or think they have) did not proclaim with such puffed-up joy statements such as "centrifugal force doesn't exist" which causes confusion and doubt in minds that are beginning to relate equations of motion to their everyday experience - this is exactly what turns intelligent, curious people away from science.
Would it not be even better if we all stuck to standard text book terms and explanations. There is no shortage of expert knowledge outside PF.

A.T.

Quote by WannabeNewton

Hmm, can't say I've ever heard of the "reactive centrifugal force". I'll read up on it thanks.

EDIT: I tried looking it up and I just found other forum links, a wiki link, and a facebook link (lol). Is there like some textbook this is discussed in? I couldn't find anything in Kleppner about it, which is the book I usually turn to, nor could I find anything in Taylor.

DaleSpam posted some books:
http://www.physicsforums.com/showthr...le#post4259305

The reason why this is not discussed much, is that there is not much to discuss. It is not some elaborate concept, just a naming convention for the 3rd Law reaction to some centripetal force.

stevendaryl

Quote by MrAnchovy

On a more serious note, what WOULD be better would be if those who have mastered the maths of non-inertial frames of reference (or think they have) did not proclaim with such puffed-up joy statements such as "centrifugal force doesn't exist" which causes confusion and doubt in minds that are beginning to relate equations of motion to their everyday experience - this is exactly what turns intelligent, curious people away from science.

I think that's baloney. Someone is going to drop out of trying to learn science because someone tells them that centrifugal force doesn't exist?

Emilyjoint

Quote by stevendaryl

I think that's baloney. Someone is going to drop out of trying to learn science because someone tells them that centrifugal force doesn't exist?

This is an opinion, not a scientific fact.

Emilyjoint

This post should end now. 30+ posts resulting from a basic misunderstanding of some very basic physics.
I think someone has already pointed out that the explanation was given in post 2.
We have now degenerated into non specific opinions which are not part of the recognised physics literature. None of the references above are available from my book store.

WannabeNewton

Quote by A.T.

DaleSpam posted some books:
http://www.physicsforums.com/showthr...le#post4259305

The reason why this is not discussed much, is that there is not much to discuss. It is not some elaborate concept, just a naming convention for the 3rd Law reaction to some centripetal force.

Thanks A.T.! I never knew it had a name. That's interesting

Not a fan of the terminology though

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Emilyjoint	This post should end now. 30+ posts resulting from a basic misunderstanding of some very basic physics. I think someone has already pointed out that the explanation was given in post 2. We have now degenerated into non specific opinions which are not part of the recognised physics literature. None of the references above are available from my book store.