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ray9394 发表于 11-6-1 12:11
Regarding to your provided equation, I believe that there is an assumption, which is, the frictional ...

That doesn't alter what the formula purports.

I think in an ideal situattion (friction = centripetal force) you are correct, you may check the assumption in your formula. But in actual case the traction can be lower than the centripetal force. If the car goes understeer or oversteer, then the radius is no longer as a constant, as well as speed. Besides, as a driver, I would prefer my car to go understeer than rollover.   

回复 anordinaryman 的帖子

This is because the car is not quick enough to generate the uplift force.

To be honest, I'm not a good racer and I do not know how to make a rear wheel drive car from understeer to more neutral when making a corner.  To my understanding, the steering characteristic of any car will affect their cornering performance and I believe they are related to this topic. As it will affect the corning speed and turning radius.

Hey, I found something really interesting, and this is about the Ford SUV again.

"The Bronco II has a 'handling' problem like many other of the small sport utility vehicles. It does friction rollovers on the highway.  A friction rollover occurs when the cornering forces - tire friction forces - generated by the driver's steering input becomes high enough to cause the vehicle to rotate around its longitudinal axis and lift the tires off the ground.

http://www.safetyissues.com/magazine/2003/2/SUV/SUV.htm

回复 ray9394 的帖子

"I think in an ideal situattion (friction = centripetal force) you are correct, you may check the assumption in your formula. But in actual case the traction can be lower than the centripetal force. If the car goes understeer or oversteer, then the radius is no longer as a constant, as well as speed. Besides, as a driver, I would prefer my car to go understeer than rollover. "

It is actually not an 'ideal' situation but an equilibrium situation Physics trying to depict (action force = reaction force).  The formula is not mine but, instead, a publicly available intellectual property that everyone can learn, challenge, or even deny.  It's all up to you.  If you don't believe in it, fine.  Check it yourself and point out what the Physicists have been wrong for nearly 300 hundred years!  In actual case when traction is lower than centripetal force, the car will simply lose control (oversteer or understeer? who knows, it all depends).  It won't bother what the driver prefers.

I know why you are so famous in the forum. Action force = reaction force is newton's third law, I know it. But this is noe necessary frictional force equal to centripetal force.  

这……还是在天朝么？难道链接到外文网站了？

回复 ray9394 的帖子

Hey, I found something really interesting, and this is about the Ford SUV again.

"The Bronco II has a 'handling' problem like many other of the small sport utility vehicles. It does friction rollovers on the highway.  A friction rollover occurs when the cornering forces - tire friction forces - generated by the driver's steering input becomes high enough to cause the vehicle to rotate around its longitudinal axis and lift the tires off the ground.

http://www.safetyissues.com/magazine/2003/2/SUV/SUV.htm


It was written for layman and well served the purpose.  It is by no means intended for a serious explanation as terms are loosely used without any specific correlation to the logical consequence of rollover that can be verifiable in physics perspective.  As a matter of fact, I browsed through the organisation (Technical Services) writting this comment and found nothing 'technical' in respect of rollover other than sale talk.  See for yourself:

http://www.e-z.net/~ts/web-6-1-06/cover.htm  

回复 ray9394 的帖子

I know why you are so famous in the forum. Action force = reaction force is newton's third law, I know it. But this is noe necessary frictional force equal to centripetal force.  


I didn't say frictional force equal to centripetal force. It was you who put it forward in 98# (and repeat in 102#) as follows:

Regarding to your provided equation, I believe that there is an assumption, which is, the frictional force is always equal to the centripetal force.


To be honest, I couldn't care less what you believe.