I really am not getting this physics stuff...again I thought I had this one figured out but it doesn't seem to be right. So the question... A 49.2 kg car is moving at 12.6 m/s around a horizontal curve whose radius is 31.3 m. What is the magnitude of the fictional force required to keep the car from sliding? and this is what I did.. I found my net force for x and y Fy = may Fy = 0 N- W = 0 N = mg Fx = max fs = max u x N = m(v^2/r) so then I substituted in my N and got u x mg = m(v^2/r) and I solved for u (frictional force...I'm just using u for the term) u x (49.2kg)(9.81m/s^2) = (49.2kg)(12.6^2/31.3m) and it works out to be 0.517 and the computer is telling me I'm wrong once again. so I must be wrong.