How Slow Should You Go on a Wet, Unbanked Turn?

[gsr_4life]

I need some help setting this up.

A car is safely negotiating an unbanked circular turn at a speed of 21m/s. The max static frictional force acts on the tires. Suddenly a wet patch in the road reduces the maximum static frictional force by a factor of three. If the car is to continue safely around the curve, to what speed must the driver slow the car?

Any hints as to setting it up would be great!

 

[andrewchang]

it involves centripetal acceleration. try drawing a free body diagram

 

[Homer Simpson]

http://laser.phys.uAlberta.ca/~freeman/enph131/fbdex3.html