RcTek : Information & Resources for the Model Car Racer

Centrifugal & Centripetal Force

Following the publicity of the proposition that centrifugal force does not exist, a proposal which stated that we should instead use the term centripetal force to explain many of the things related to model cars, we have put together this article to try to explain this apparent about turn in thinking.

We have no plans to change our references on the site for the reasons given after the declaration that There is No Such Thing As Centrifugal Force

Article Notes

The drawings in this article depict a clutch which would have to be rotating for the forces to be generated that enable the movements of the clutch shoes. The rotation of the clutch has been left out as it would have added unnecessary confusion.

Centrifugal Force

The majority of model car racers out there are familiar with the term centrifugal force, a term derived from the Latin for ‘centre fleeing’ which is defined in the Oxford English Dictionary as;

“Moving or tending to move away from a centre, (the inertial force causing) the tendency of a body rotating about a centre to move outwards from that centre.”

Shown on the right is an animation of a clutch and using the definition given above you can determine that the clutch shoes (yellow) are thrown in the direction of the arrows (red) by the centrifugal force to contact the clutch bell (blue). If you Play the animation you will see this force in action.

Centripetal Force

Now that we have defined and demonstrated centrifugal force we can move onto centripetal force, a term the majority of model car owners will not be familiar with.

This term, derived from the Latin for ‘centre seeking’ is also defined, interestingly enough, in the Oxford English Dictionary as the exact opposite of centrifugal force.

The animation on the right shows the same clutch but the arrows (red) show how centripetal force acts through the clutch bell (blue) to contain the movement of the clutch shoes (yellow). If you Play the animation you will see this force in action.

Confused?

The use of a model car clutch for demonstrating this declaration is a good one (IMHO) for our justification for not changing our references to centrifugal force.

For the sake of simplicity, it is easier and more logical to understand that the clutch bell is responsible for stopping the shoes from continuing moving outwards, just as it is easier to understand that the ground beneath your feet stops you from falling through the Earth.

How Do They Justify Their Case?

The physicists have taken Sir Isaac Newton's observation into account that any object will continue to travel in a straight line unless acted upon by an external force.

Playing the animation on the right illustrates why they justify that there is no such thing as centrifugal force. Imagine you had been to the shops and had left a box on the roof. You set off slowly and build up speed, the box on the roof is held in place mainly by the force (red arrow) bearing down upon it. At the exit to the car park you turn sharply, at which point the box has the forward momentum of the car, but does not have the external turning force that the tyres provide. As there is no sideways retaining force, the box continues on its straight path and is sent to the ground by the forces acting upon it.

Related Information

There is No Such Thing As Centrifugal Force

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© 2001, 2009 by Darren Burnhill