Circular Motion while learning to drive

[haha1234]

Homework Statement

While learning to drive,you are in a 1200 kg car moving at 20.0m/s across a large,vacant,level parking lot.Suddenly you realize you are heading straight toward the brick sidewall of a large supermarket and are in danger of running into it.The pavement can exert a maximum horizontal force of 7000N on the car.
Explain why you should expect the force to have a well-defined maximum value.

Homework Equations

The Attempt at a Solution

The answer state that the maximum value determined by the surface roughness.Why the roughness of the road make the force well-defined?

 

[Doc Al]

What kind of force do you think is stopping the car?

(What does this question have to do with circular motion?)

 

[haha1234]

What kind of force do you think is stopping the car?

(What does this question have to do with circular motion?)

ioc.
And i want ask another question,why the minimum distance required to avoid collision when not applying brakes and turning the steering wheel is twice as that of applying brakes and not turning the steering wheel?
Sorry for my poor English and I hope that you can understand what I mean.:shy:

 

[Doc Al]

ioc.

?

And i want ask another question,why the minimum distance required to avoid collision when not applying brakes and turning the steering wheel is twice as that of applying brakes and not turning the steering wheel?

Figure out the required distance in each case and see for yourself! Hint: When turning the wheel, the force is centripetal.