# Centrifugal vs. Centripetal

**URL:** <https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656>\
**Category:** Factual Questions\
**Created:** [May 2, 2003, 4:39pm UTC](https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656 "2003-05-02T16:39:19Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![KnK](https://avatars.discourse-cdn.com/v4/letter/k/edb3f5/32.png) [@KnK](https://boards.straightdope.com/u/KnK)\
**Post date:** [May 2, 2003, 4:39pm UTC](https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656/1 "2003-05-02T16:39:19Z")

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Hey there, first time poster here so be gentle 😉

At a recent family gathering, the subject of centripetal force came up. One family member insisted that centrifugal force does not exist, and that centripetal force is the only force (in this context). This member insisted that when people generally refer to centripetal force, they are in fact wrong and that they should really be saying centripetal force instead. Two other opposing family members insisted that centrifugal force is the force imposed AWAY from the center, and that it opposes centripetal force that imposes a force TOWARD the center. Kind of a “you cant have one without the other” type of thing.

Who is correct?

KnK

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**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\
**Post date:** [May 2, 2003, 7:36pm UTC](https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656/2 "2003-05-02T19:36:14Z")

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I donno if my answer helps you - but here it is:

Centrepetal force is the force required for any body to follow a circular path. So if u take a rock, tie it to the string and swirl it around, the centripetal force (the tension in the string) is keeping the rock in its path. You provide this tension to the string, which is the centripetal force. Now another way of looking at it would be that the rock is pulling at u - so the rock is exerting the force on you in which case you will call it centrifugal force.

Centrifugal force is sometimes called a pseudo force, because it arises from choosing your reference system (the rotating body).

PS : Newtons laws are not valid in non Inertial system (the rotating body being such a system.)

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**Author:** ![Ice\_Wolf](https://avatars.discourse-cdn.com/v4/letter/i/dfb087/32.png) [@Ice\_Wolf](https://boards.straightdope.com/u/Ice_Wolf)\
**Post date:** [May 2, 2003, 7:36pm UTC](https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656/3 "2003-05-02T19:36:17Z")

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WElcome to the SDMB, **KnK**.

[Looks like the two forces are associated.](http://www.bartleby.com/64/C004/015.html)

> [@](#):
>
> For example, if you hold a bucket of water by the handle and spin in a circle, you can feel the bucket pull your arms away from the center of your rotation. This is the centrifugal force and is a result primarily of the inertia of the bucket and the water. The effort that it requires to hold onto the bucket and keep spinning is the source of the centripetal force. You can “feel” the centrifugal force in this example, and you can observe (due to the circular motion) that a centripetal force is present.

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**Author:** ![John\_Kentzel-Griffin](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@John\_Kentzel-Griffin](https://boards.straightdope.com/u/John_Kentzel-Griffin)\
**Post date:** [May 2, 2003, 9:24pm UTC](https://boards.straightdope.com/t/centrifugal-vs-centripetal/172656/4 "2003-05-02T21:24:43Z")

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Duplicate of [Centrufugal vs. Centripetal](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=181345)

I’ll close this one.

**DrMatrix** - GQ Moderator