I Fictitious forces -- name convention

[Trying2Learn]

Hello all,

I understand there are four d'Alembert (fictitious) (non-inertial) forces:
1. Coriolis
2. Centrifugal
3. Linear
4. Angular acceleration.

But then I think about the Gyroscopic Effect (I understand how it arises, so that is not the issue).

I am wondering if one can "classify" these (with a word!)... and how.

Do we have four FUNDAMENTAL (non-inertial) forces?
Is the gyroscopic effect a compound of them?

Is there one generally accepted word for the four above that come from the second derivative of a moving reference frame, and a different word for one like the gyroscopic effect?

 

[jbriggs444]

It seems to me that there are roughly as many distinct fictitious forces as there are ways to parameterize the acceleration of a non-inertial reference frame.

 

[Trying2Learn]

It seems to me that there are roughly as many distinct fictitious forces as there are ways to parameterize the acceleration of a non-inertial reference frame.

So does that mean we consider the four I listed above as "fundamental?"
Is there a "word" to "classify" those four?

 

[jbriggs444]

So does that mean we consider the four I listed above as "fundamental?"
Is there a "word" to "classify" those four?

Why should anyone care?

 

[Trying2Learn]

Why should anyone care?

I care. I am just interested.

 

[jbriggs444]

I care. I am just interested.

OK. So you want to know whether these four are the only "fundamental" fictitious forces. Since you used the word, what does "fundamental" mean to you in this context?

Personally, I consider the notion of "fundamental" in the context of a fictitious force to be an oxymoron. None of the forces are fundamental. They arise from the a choice of coordinates and are not even physical. The fundamentals are the parameterizations of coordinate system accelerations. The resulting fictious forces are then mere mathematical consequences of those choices.

 

[Trying2Learn]

OK. So you want to know whether these four are the only "fundamental" fictitious forces. Since you used the word, what does "fundamental" mean to you in this context?

I do not know.

I just want to know if there is a way to classify the four that come from taking the second derivative of the position of a particle in a moving reference frame, from one like the gyroscopic effect, which is way more involved.

 

[A.T.]

I understand there are four d'Alembert (fictitious) (non-inertial) forces:
1. Coriolis
2. Centrifugal
3. Linear
4. Angular acceleration.

What about the Euler force?
https://en.wikipedia.org/wiki/Euler_force

Also, in Earth science the Coriolis force as known in physics is decomposed into the Coriolis effect (parallel to the Earth's surface) and the Eötvös effect (normal to the Earth's surface).
https://en.wikipedia.org/wiki/Eötvös_effect

You can make up as many names as you for the various components and terms of inertial forces. There is nothing fundamental about any of these.

 

[A.T.]

from one like the gyroscopic effect, which is way more involved.

What does the "gyroscopic effect" have to with that? It is observed in inertial frames as well, where there are no inertial forces.

 

[Trying2Learn]

What about the Euler force?
https://en.wikipedia.org/wiki/Euler_force

Also, in Earth science the Coriolis force as known in physics is decomposed into the Coriolis effect (parallel to the Earth's surface) and the Eötvös effect (normal to the Earth's surface).
https://en.wikipedia.org/wiki/Eötvös_effect

You can make up as many names as you for the various components and terms of inertial forces. There is nothing fundamental about any of these.

Well the Euler is another name for just the angular acceleration

Then you have this new name I never heard ( Eötvös)

But that still leave me to ponder why there are only four that come from the two derivatives to get acceleration.

All the others seem to be built up from them.

 

[Trying2Learn]

What does the "gyroscopic effect" have to with that? It is observed in inertial frames as well, where there are no inertial forces.

By this, I mean the following...

One has the spin and the precession and then it INDUCES a nutation. This nutation is not an applied force, but comes from the combination of spin and precession.

 

[A.T.]

Well the Euler is another name for just the angular acceleration

By this logic they are all just alternative names for the frame's acceleration.

 

[A.T.]

By this, I mean the following...

One has the spin and the precession and then it INDUCES a nutation. This nutation is not an applied force, but comes from the combination of spin and precession.

Whatever you mean, if it exist in an inertial frame as well, then you don't inertial forces to explain it.

 

[Trying2Learn]

By this logic they are all just alternative names for the frame's acceleration.

Well... I don't know... Euler is a name given to one of the four that come from the two derivatives...

If you go here
https://en.wikipedia.org/wiki/Fictitious_force

You see there are "four" fictitious forces

I am hoping if the following is true:
There are four fundamental fictitous forces that come from Newton's law in a moving frame... but there are many than can be experienced and built up from them

 

[A.T.]

what does "fundamental" mean to you in this context?

I do not know.

I am hoping if the following is true:
There are four fundamental fictitous forces ...

Why do you hope that, if you don't even know what that would mean?

 

[Trying2Learn]

Why do you hope that, if you don't even know what that would mean?

There is no need to be sarcastic.

I am trying to understand something, but lack the words to assert the question.

 

[Nugatory]

I am hoping if the following is true:
There are four fundamental fictitous forces that come from Newton's law in a moving frame... but there are many than can be experienced and built up from them

You are putting too much weight on the historical accident that some fictitious forces have names of their own. They have names because they appear in many interesting problems, and assigning names to things that we talk about a lot is a natural part of the development of language.

This line of thought is no more likely to be productive than wondering why there are two classes of animals: those for which there are different English words for the male and female ("ram" and "ewe", "mare" and "stallion", "buck" and "doe", ...) and those for which there are not (rats, pangolins, opossums, ...). Sorting all animals into those two classes tells us only that at some point during the development of the English language it was convenient to think differently about the male and female of some animals and not others.

 

[Trying2Learn]

You are putting too much weight on the historical accident that some fictitious forces have names of their own. They have names because they appear in many interesting problems, and assigning names to things that we talk about a lot is a natural part of the development of language.

This line of thought is no more likely to be productive than wondering why there are two classes of animals: those for which there are different English words for the male and female ("ram" and "ewe", "mare" and "stallion", "buck" and "doe", ...) and those for which there are not (rats, pangolins, opossums, ...). Sorting all animals into those two classes tells us only that at some point during the development of the English language it was convenient to think differently about the male and female of some animals and not others.

Thanks! That was what I was looking for.

 

[Dale]

Do we have four FUNDAMENTAL (non-inertial) forces?

There are no fundamental non inertial forces. Non inertial forces arise from non inertial frames. There is no limit to the different inertial frames you could have, so there is no finite “basis set” that you could use to build up inertial forces.

 

[Trying2Learn]

There are no fundamental non inertial forces. Non inertial forces arise from non inertial frames. There is no limit to the different inertial frames you could have, so there is no finite “basis set” that you could use to build up inertial forces.

And thanks again... That was also the phrasing that worked for me.