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CarDoc, Independent European Shop owner
Category: Car
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Experience:  20 years of experience working with European cars. Independent European shop owner and technician.
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Fargason: Why is the centripetal force of a car going around

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Why is the centripetal force of a car going around a curve equal to the static frictional force? I got this from my physics class, but I don't understand the actual physical meaning. If there is a static frictional force pointing towards the center of the curve, that has to mean that there is a force pushing in the opposite direction to the curve that the static frictional force is opposing, but I don't know what that is.

CarDoc :

Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.

CarDoc :

The centripetal force is only equal to the static frictional force to a point, that point being where the tires lose adhesion...


CarDoc :

in most cases of regular road cars, this force is going to be about .80-.90g


CarDoc :

the opposite force is going to be centrifugal force, meaning a vector pointing from the apex of the corner, outward


CarDoc :

I'd like to keep this chat open, if you're able to access it, otherwise I'll change to standard email format


CarDoc :

please let me know if you have further questions. Switching formats now


CarDoc and 2 other Car Specialists are ready to help you
Customer: replied 4 years ago.

When you say that the tires loose adhesion at 0.8-0.9 grams, (Is it grams?) where are you getting numbers? Do they relate to vectors pointing out from the center of the circle? Is that how people find the coefficients for static and kinetic friction?

Not grams. G=force of gravity. 1 g lateral, would be a force vector pointing from the apex of the circle outward, perpendicular to the force of gravity.

The numbers are going to be different for every car and every tire. We'll take 2 extremes.
1975 Buick Electra, on period-correct tires, can generate a maximum of approximately 0.60g lateral
2012 Renault Formula 1 car can generate about 4-5 g lateral.