What I'm doing seems like it should work, but I can't seem to get it right. I'm sure I'm doing the math right, but I have a feeling I'm answering something that's not being asked. I would just like some help on setting up the equation right. A car starts from rest on a flat circular track of radius 200.1 m and accelerates tangentially at a rate of 4.79 m/s2. How much time elapses before the centripetal acceleration of the car is equal in magnitude to the tangential acceleration. I have the tangential acceleration (at), and radius (r). Using the centripetal acceleration equation ac=v2/r, I set ac=4.79 m/s2, r=200.1m, and solve for the velocity. I then use the circular motion period equation (v=(2*pi*r)/t), plug in the velocity I just calculated, the radius of the track, and solve for time. I get 40.61s everytime, which is incorrect. vv I got it now. Thanks for saving my hair.