Homework Help: Circular Motion while learning to drive

1. Dec 28, 2013

haha1234

1. The problem statement, all variables and given/known data

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.

2. Relevant equations

3. 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?

2. Dec 28, 2013

Staff: Mentor

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

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

3. Dec 28, 2013

haha1234

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:

4. Dec 28, 2013

Staff: Mentor

?

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