[SOLVED] Vertical Circular Motion & Centripetal Acceleration 1. The problem statement, all variables and given/known data 1) A car travels at a constant speed around a circular track whose radius is 2.1 km. The car goes once around the track in 410 s. What is the magnitude of the centripetal acceleration of the car? 2. Relevant equations a=(v^2)/r 3. The attempt at a solution a=((2100/410)^2)/2100=0.01249 - wrong answer --- 1. The problem statement, all variables and given/known data 2)A roller coaster at an amusement park has a dip that bottoms out in a vertical circle of radius r. A passenger feels the seat of the car pushing upward on her with a force equal to five times her weight as she goes through the dip. If r = 20.5 m, how fast is the roller coaster traveling at the bottom of the dip? 2. Relevant equations F-mg = m(v^2/r) 3. The attempt at a solution v^2 = (20.5)(9.8) v = 14.17 m/s - wrong answer --- Please help me, I don't know what I'm doing wrong.