Centripetal force

[GuavaHalf]

I was taught at school that there is no such thing as centrifugal force - it is just an imaginary force used to make explanations simpler.

eg washing in a spin dryer is not thrown outwards by centrifugal force, insread it is constantly being prevented from proceed in at a constant speed in a straight line by centripetal force. ie the drum keeps the clothes in.

This make much more sense to me so why do people still insist on explanations using a non existant force?

[Tweed]

That's right, all 'centrifugal' force is just an effect of inertia. The real force acting is centripedal.

[mr. piper]

sorry you mean "CENTRIPETAL"

[Hippy]

Quite right, GustavHalf, centripetal form the Latin "centre seeking" is the inward force exerted on the clothes by the drum stopping them from flying out in a straight line, and so effectively pushing them towards the centre.

 

Now I wonder what is flinging the clothes out in that straight line? Why of course, it is the momentum transferred from the spinning drum, and the clothes end up at the edge because the mass of clothes wishes to maintain its angular momentum and fly out. This is, as has been stated, inertia.

 

If the clothes were released from the constraints of the drum, and there were no other barriers to motion, the items would attempt to whiz off along a line tangential to the outer drum with the tangent's point of contact where the clothes escaped the drum's constraint. This is what, for years, has been called "Centrifugal Force". It is a force that appears to cause a body travelling round a central point to fly outwards from its circular path. It is indeed another name for inertia.

 

In my explanation of the gasses in the rotating tube I wished to explain why the more dense gases would press the less dense gasses towards the centre of rotation. It is the denser gasses' movement outwards and being confined by the centripetal force exerted by the sides of the tube that squashes the flame inwards. This squash is exerted by the denser gas possessing more momentum as its mass is greater. Calling this "Centrifugal" is more readily understood than the more lengthy exposition on inertia.

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[GuavaHalf]

Hippy - my question was not intended to put down your answer to the candle question. Your answer just reminded me of something I've been meaning to ask.

Would it be better to call it centrifugal inertia rather than a 'force'?

[Hippy]

Or then again, why not call it aquired momentum? All a bit daft when you consider that a flywheel continues to turn well after the power is removed because of inertia, and yet there is nothing "inert" about it!

 

I took no offense, GuavaHalf, I was enjoying the jolly debate that still exists about the apparent force we call Centrifugal. It's there, we can feel it, so it must exist! But no logical or scientific evidence can prove its existence. Indeed, a simple scientific demonstration is all that is needed to show how the illusion arises. However, that demonstration would have to be conducted so many times in so many places before the ghost of Centrifugal force is laid.

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[Bonzo 2000]

As an aside, I think the same situation exists with suction.  I was always taught that there is no such thing as suction, but that it is a perception to help explain the effects of unequal pressure.  If your hand sticks to the nozzle of a vacuum cleaner, its not suction, but the effects of higher pressure under your skin pushing towards the lower pressure atmosphere within the tube.  So there we have it - suction, centrifugal force - all a lot of nonsense.

[Gerry Baby]

I am not submitting an answer, but just to say thanks for the easily digestible explanations you dudes have offerd for the above question.  I have learned something new this cold and windy lunch time.

[magicdice]

"centrifugal force" is the fault of the chemists & their centrifuge, which requires a centripetal force

 

centripetal force exists, but it's a term used to describe the way that another force (friction, inertia) works to give a certain effect.

[robojoos]

so if the drum and the clothes did not have a frictional force with each other, would the clothes just fall to the bottom?

[alangdon]

I have enjoyed reading this, and it is what I have always thought. Could someone comment on the equally convincing (to me, at least) answer to this question supplied at this link?

http://www.thekeyboard.org.uk/What%20is%20centrifugal%20 force.htm