A flat (unbanked) curve on a highway has a radius of 220.0 m. A car rounds the curve at a speed of 21.0 m/s. What is the minimum coefficient of friction that will prevent sliding? Suppose the highway is icy and the coefficient of friction between the tires and pavement is only one-third what you found in part A. What should be the maximum speed of the car so it can round the curve safely? Can someone help me. I don't know what to do for the second part. I found the minimum coefficient to be .205 but i cant find the maximum speed. Is the equation squareroot of coefficient of friction divided by radius?