1. The problem statement, all variables and given/known data At what angle should the roadway on a curve with a 50m radius be banked to allow cars to make the curve at 12 m/s even if friction is 0? 2. Relevant equations 3. The attempt at a solution All of the centripetal acceleration comes from normal force from the road on the car. I choose to represent the road as being along the y axis and Fn as being along +x axis. Then gravity is directed at angle theta to the left of the -yaxis. Normal force must equal the component of gravity along -xaxis, which is mgsin(theta), Since the required centripetal force is mv^2/r, this is 2.88m, mgsin(theta) = 2.88m gsin(theta) = 2.88 theta = 17.09 My professors work seems to be similar, but at the end she says that: gtan(theta) = 2.88 theta = 16.37 why?