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| Heinsbergrelatz |
 Posted: Thu Oct 08, 2009 2:46 am Post subject: Centrifugal & Centripetal force |
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Forum Junior
Joined: 01 Aug 2009
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Location: Singapore
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can anyone explain clearly the difference between the two terms, (with examples would be great.)
thank you |
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| Bender |
| Posted: Thu Oct 08, 2009 4:30 am Post subject: |
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Joined: 03 Dec 2008
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The centrifugal force doesn't exist.
The centripetal force is the name for a force which causes the direction of the velocity of an object to change. It is used most often in a circular motion in which the direction of the velocity changes continuously.
Because the centripetal force is oriented perpendicular to the velocity it doesn't use energy.
The term is often used in circular motions, where the centripetal force points to the centre of the circle.
Note: the confusion originates from the fact that when you are in a car which is taking a turn, you seem to experience a "force" outwards. What is happening in reality is that your body just wants to continue its course due to inertia, but your seat is exerting a centripetal force inwards to drag you in a curve.
Note 2: in rotating (thus non-inertial) reference frames, a virtual "centrifugal force" has to be included in calculations. It has no reaction force, and thus doesn't comply to the 3rd postulate of Newton. Only use this in more advanced calculations. |
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| Booms |
| Posted: Thu Oct 08, 2009 11:49 pm Post subject: |
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Joined: 04 Sep 2008
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Centrifugal Doesn't exist, it's the senstation of being thrown outwards
Centripetal does exist, it's the force the string exerts on a brick you are swinging round your head to change it's direction
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| Snoogy |
| Posted: Fri Oct 09, 2009 1:33 am Post subject: |
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Joined: 08 Oct 2009
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| in the railway industry they say that the centifugal force is what keeps trains on the track as they travel around a curve, if it does not exist, what force is causing this? |
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| Bender |
| Posted: Fri Oct 09, 2009 6:58 am Post subject: |
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| Snoogy wrote: |
| in the railway industry they say that the centifugal force is what keeps trains on the track as they travel around a curve, if it does not exist, what force is causing this? |
Centripetal force.
I don't know who you're referring to when you say "the railway industry", but they are wrong. |
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| Booms |
| Posted: Sat Oct 10, 2009 3:26 pm Post subject: |
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| Snoogy wrote: |
| in the railway industry they say that the centifugal force is what keeps trains on the track as they travel around a curve, if it does not exist, what force is causing this? |
Yah the whole world is under the impression that centrifugal force exists
we are here to tell you the whole world is wrong and us boffins are right
basically centrifugal and petal forces are one and the same, it's pretty much just nitpicking over words, as I said in my post above centrifugal force is the senstation of being flung outwards, centripetal is the actual force deviating you from your original course
and whatever 'rail company' told you this would be very dogey, I wouldn't use them, 'centrifugal' force is what trains have to overcome to stay on the tracks, not what holds them on
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| Heinsbergrelatz |
| Posted: Sun Oct 11, 2009 7:23 am Post subject: |
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Joined: 01 Aug 2009
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thank you for all responses, i now have alittle sense on what they are
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| Sophie |
| Posted: Sat Oct 17, 2009 10:15 am Post subject: |
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Joined: 17 Oct 2009
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More precisely, centrifugal force is an inertial or “fictitious” force (rather than nonexistent force). It is a force that manifests itself in an accelerated frame of reference.
Whether a force is centripetal or centrifugal. If you look at an object undergoing circular motion from a (non-accelerated) reference frame outside the object, then you see a force on the object directed towards the centre of its circular orbit; this force is the centripetal force. On the other hand, if you consider the motion from the point of view of the object itself, then you feel a force directed away from the centre; this would be a centrifugal force. In the latter case, your frame of reference is itself moving in a circle and is thus an accelerated reference frame.
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| Chronman |
| Posted: Sat Oct 17, 2009 3:05 pm Post subject: |
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Centripetal is inward, centrifugal outward.
Centripetal is the force that exists for every body being rotated.
Centrifugal is a pseudo-force, or as the poster above mentioned, "fictitious", it exists, but to avoid complications/confusion, it doesn't exist. |
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| Bender |
| Posted: Sat Oct 17, 2009 4:33 pm Post subject: |
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| Sophie wrote: |
| Whether a force is centripetal or centrifugal. If you look at an object undergoing circular motion from a (non-accelerated) reference frame outside the object, then you see a force on the object directed towards the centre of its circular orbit; this force is the centripetal force. On the other hand, if you consider the motion from the point of view of the object itself, then you feel a force directed away from the centre; this would be a centrifugal force. In the latter case, your frame of reference is itself moving in a circle and is thus an accelerated reference frame. |
And the word centrifugal should only be used by and to people that know this.
Note that in a rotating frame of reference there is a 'ficticious' centrifugal force on every object, but you won't call it a 'centrifugal' force for these other objects.
I don't agree that it exists, though. In my opinion, it is a only mathematical artefact. |
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