QUESTION:A car travels at a speed of 16 m/s around a curve of radius 21 m. The acceleration of gravity is 9.8 m/s^2 : http://img262.imageshack.us/img262/3067/bankedcurvera4.jpg [Broken] What is the net centripetal force needed to keep the car from skidding sideways? Answer in units of N. if there was no friction, what centripedtal force could be provided just by the banking of the road? ANSWER: http://img523.imageshack.us/img523/4331/bankrz7.jpg [Broken] i used 2 eqns for this by dividing all the forces into separate components. y-direct: mg+fcos72=ncos18 x-direct: mv^2/r=nsin18+fsin72 i used those and found n=32718.5452 f=21413.6627 coeff of frict=.65448 net centripetal=30476.19 i found all of the above for the other parts of the question, and they are all correct. But the question i presented above confused me. If no friction is present, the only force contributing to centripetal force would be the normal force. so that'd be nsin18, but it wasn't right. what am i thinking wrong here?