Given
Mass of the car, m=1250 kg
Speed of the car, v=22 m/s
To find
a. Centripetal acceleration of the car
b. The radius of the smallest circle.
Step-by-step explanation
a. Given the radius is r=35 m
The centripetal acceleration is given by

b. The frictional force is F=20,000N
The speed is v=22 m/s
Thus,

Conclusion
a. The centripetal acceleration is

b.The radius is 30.25 m