# No such thing as centrifugal force?
**URL:** https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138
**Category:** Cecil's Columns/Staff Reports
**Created:** [July 22, 2003, 1:40pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138 "2003-07-22T13:40:58Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@x-ray\_vision](https://boards.straightdope.com/u/x-ray_vision)
#### Post date: [July 22, 2003, 1:40pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/1 "2003-07-22T13:40:58Z")
In Cecil’s answer to [What happens if the earth stops spinning?](http://www.straightdope.com/classics/a961122a.html), Cecil makes the statement, “(And please, don’t tell me there’s no such thing as centrifugal force. I know that. I just don’t feel like going into a long explanation.)” Is this true? There’s no such thing as centrifugal force?
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### Author:  [@AHunter3](https://boards.straightdope.com/u/AHunter3)
#### Post date: [July 22, 2003, 4:09pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/2 "2003-07-22T16:09:05Z")
That is correct. “Centrifugal force” is an illusion composed of inertia and momentum. At any given moment the rock in your sling is being _forced to change directions_ as you whirl it around. Left to its own devices, it would continue in a straight line, but a split second later the sling has changed the angle of what that straight line would be. The illusion is that the rock wants to fly to the “outside” of the circle it is making. The truth is that it wants to keep going in the precise direction it’s headed, which at any given moment is at a 90° angle to the direction that “outside” would be. In other words, if you’re in the process of taking down that Goliath dude, you better release the stone _not_ when the stone is extended as far towards his ugly face as possible but instead when it is at right angles and coming from behind – at that moment it is headed for old G over there, and when you release it from its imprisoning sling it continues in that direction until it transfers its energy to G’s schnozzola.
In the case of planets and satellites and whatnot, substitute gravity for the sling. They aren’t trying to “escape” orbit, they’re just trying to continue in a straight line and gravity keeps yanking their chain and pulling that line around to a new angle.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [July 22, 2003, 6:04pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/3 "2003-07-22T18:04:38Z")
…However, if you’re using a co-rotating reference frame, then you don’t realize that you’re changing directions, since you don’t realize that you’re moving at all (since, in fact, in that reference frame, you really aren’t moving at all). But then you’ve got to explain the fact that you’re feeling a force, apparently pulling you to the outside of the circle. This is what’s called centrifugal force, and it’s perfectly correct to use it, if you’re in the rotating reference frame. Since Cecil was working in an Earth-based reference frame, and the Earth is rotating, it was correct for him to use centrifugal force.
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### Author:  [@The\_Bad\_Astronomer](https://boards.straightdope.com/u/The_Bad_Astronomer)
#### Post date: [July 23, 2003, 3:21am UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/4 "2003-07-23T03:21:07Z")
I will simply say that **Chronos** is correct, and it makes me nuts when people flatly say it doesn’t exist.
Also, this topic has been covered before on this board; try a search on it and you’ll see other threads where we have gone over it.
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### Author:  [@x-ray\_vision](https://boards.straightdope.com/u/x-ray_vision)
#### Post date: [July 23, 2003, 10:44pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/5 "2003-07-23T22:44:42Z")
Did a search **Astronomer** , found nothing. Does this mean I’ve actually found a mistake made by Cecil? 😉
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [July 23, 2003, 11:05pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/6 "2003-07-23T23:05:58Z")
[Improve](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=191792) [your](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=181345) [search](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=155454) [skills,](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=49386) [**x-ray vision**.](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=33236)😃
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### Author:  [@Ponder\_Stibbons](https://boards.straightdope.com/u/Ponder_Stibbons)
#### Post date: [July 25, 2003, 1:21pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/7 "2003-07-25T13:21:55Z")
So, in other words, of course centrifugal force exists … except, of course, it doesn’t.
I think this is a classic case of semantic disconnect. Whether centrifugal force “exists” depends entirely on how one defines it.
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### Author:  [@AHunter3](https://boards.straightdope.com/u/AHunter3)
#### Post date: [July 25, 2003, 2:29pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/8 "2003-07-25T14:29:55Z")
That depends on what you mean when you say “exists”.
owww!
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [July 25, 2003, 4:18pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/9 "2003-07-25T16:18:38Z")
Let me make things simple: Centrifugal force is exactly as real as gravity. I’ll accept a person arguing that neither is real, and I’ll accept an argument that both are real, but it’s incorrect to say that gravity is real and c. f. isn’t, or that gravity is “more real” than c. f.
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### Author:  [@x-ray\_vision](https://boards.straightdope.com/u/x-ray_vision)
#### Post date: [July 25, 2003, 10:16pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/10 "2003-07-25T22:16:57Z")
Thanks for **always** being here **Q.E.D.** , none of the links you posted seemed that that they would answer my question by their titles, but thanks for telling me to improve my search skills. 🙂
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### Author:  [@Wolfrick](https://boards.straightdope.com/u/Wolfrick)
#### Post date: [July 26, 2003, 4:42pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/11 "2003-07-26T16:42:22Z")
Okay, semantic rehash time…
“Centrifugal force” is an _apparent_ force, but it is not a real force.
Gravit is a real force. It produces acceleration in a line directly between the two masses in consideration.
Centrifugal force is an “apparent” force, percieved as a tension between the swinger and swingee. But if the link between the two is severed, the swingee (and swinger, too) will move away, not in a direct line between the two, but on tangent.
If Centrifugal force were “real” there would be an acceleration. It is just an illusion.
Maybe it would be better to speak of “centrifugal tension” to describe the effect.
~Wolfrick
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### Author:  [@Ring](https://boards.straightdope.com/u/Ring)
#### Post date: [July 27, 2003, 5:48pm UTC](https://boards.straightdope.com/t/no-such-thing-as-centrifugal-force/190138/12 "2003-07-27T17:48:56Z")
> [@](#):
>
> If Centrifugal force were “real” there would be an acceleration. It is just an illusion.
That’s good to know, maybe you should correct this guy.
> [@](#):
>
> “Can gravitation and inertia be identical? This question leads directly to the General Theory of Relativity. Is it not possible for me to regard the earth as free from rotation, if I conceive of the centrifugal force, which acts on all bodies at rest relatively to the earth, as being a “real” gravitational field of gravitation, or part of such a field? If this idea can be carried out, then we shall have proved in very truth the identity of gravitation and inertia. For the same property which is regarded as inertia from the point of view of a system not taking part of the rotation can be interpreted as gravitation when considered with respect to a system that shares this rotation. According to Newton, this interpretation is impossible, because in Newton’s theory there is no “real” field of the “Coriolis-field” type. But perhaps Newton’s law of field could be replaced by another that fits in with the field which holds with respect to a “rotating” system of co ordinates? My conviction of the identity of inertial and gravitational mass aroused within the feeling of absolute confidence in the correctness of this interpretation.”
>
> Albert Einstein
underlining mine