A race car rounds a curve at 55 m/s. The radius of the curve is 418 m, and the car's mass is 615 kg. (Assume the car's speed remains constant. Take the radially inward direction to be positive. Indicate the direction with the sign of your answer.) (a) What is the car's (centripetal) acceleration? 2 m/s What is it in 9's? 9 (b) What is the centripetal force acting on the car? N