1. The problem statement, all variables and given/known data As we know, if a car accelerate on curve at certain speed, it will tilt outside the circle track. So i sketch this 2 picture to show how (for me) it works. http://img193.imageshack.us/img193/2323/66057246.jpg [Broken] http://img194.imageshack.us/img194/9272/96495741.jpg [Broken] I just wondering, how can the car tilt or flip outside the circle track if the side force (centripetal force) is pointing inside the circle? 2. Relevant equations My suggestion: Total Moment about tyre (2); ∑M2=0 3. The attempt at a solution So, Fs*h + G*b/2 - FN1*b = 0 I assume that FN1=0 since the car is about to tilt about tyre (2). So here come the problem. Fs = - G*b / 2h. The minus sign shows that the side force, Fs, should point outside the circle. Any comments?