A highway curves to the left with radius of curvature R = 25m. The highway's surface is banked at 27 degrees so that cars can this curve at higher speeds. Consider a car of mass 1800kg whose tires have a static friction coefficient of 0.62 against the pavement. Take g=9.8. How fast can the car take this curve without skidding to the outside of curve? answer in m/s. I tried this problem and got it to be 15.7 m/s, but when I submitted it, it was wrong. I treat the direction going down the bank to be the positive direction. I said that the forces acting in the positive direction where the force due to static friction (9.8*1800*cos(27)*.62) and the force due to gravity (9.8*1800*sin(27)). I said for the car not to go off the outside of the curve, the forces going in the positive direction have to be equal to mv^2/R, which is centripetal acceleration. So I solved for v and got 15.7 but its wrong. What did I do wrong?