A Banked Curve in a Roadway Is Designed for a Speed

Multiple Choice

A banked curve in a roadway is designed for a speed of 35 mph. During an ice storm cars should be able to safely negotiate this curve at 35 mph, because at this speed

A) the necessary centripetal force is supplied entirely by gravity.
B) (and at all speeds) the acceleration vector of the car points down, helping maintain stability.
C) the necessary centripetal force is supplied entirely by the normal force from the road.
D) the centrifugal force of the car exactly balances the centripetal force.