Does a Tire's Point of Contact Have Zero Tangential Acceleration?

[elyons]

A car is moving foreword with a constant acceleration. I know the point of the tire in contact with the ground has a velocity of 0 (relative to the ground). Is the tangential acceleration at this point also zero? I came across an example problem in my text where this occurs and and it does not make sense to me conceptually. If someone could give me a brief explanation I would very much appreciate it. Thanks.

 

[SammyS]

What is the motion of the point of contact immediately before and immediately after it it makes contact?

 

[elyons]

So the acceleration hits zero because it is changing from negative to positive but has an identical magnitude on both side of the point of contact? So the point has a tangential acceleration relative to the center of the wheel just not to the ground?

 

[SammyS]

So the acceleration hits zero because it is changing from negative to positive but has an identical magnitude on both side of the point of contact? So the point has a tangential acceleration relative to the center of the wheel just not to the ground?

What is changing from negative to positive?

 

[elyons]

The tangential acceleration in terms of a fixed coordinate system. The velocity is accelerated to 0 as a point on the tire approaches the point of contact on the ground and after it reaches the point it is accelerated positively to increase the velocity of that point again. So at the instant the point is in contact with the ground the acceleration is 0. Sorry if I am not explaining my question clearly but writing it out like this I think I have worked it out so this helped! Thanks.