A Car Traveling at a Steady 20 M/s Rounds an 80-M

Multiple Choice

A car traveling at a steady 20 m/s rounds an 80-m radius horizontal unbanked curve with the tires on the verge of slipping.What is the maximum speed with which this car can round a second unbanked curve of radius 320 m if the coefficient of static friction between the car's tires and the road surface is the same in both cases?

A) 160 m/s
B) 80 m/s
C) 70 m/s
D) 40 m/s
E) 30 m/s