1. The problem statement, all variables and given/known data A uniform disk with radius 0.390m and mass 27.0kg rotates in a horizontal plane on a frictionless vertical axle that passes through the center of the disk. The angle through which the disk has turned varies with time according to θ(t)=( 1.50rad/s)t+( 9.00rad/s2)t2 . What is the resultant linear acceleration of a point on the rim of the disk at the instant when the disk has turned through 0.100rev ? 2. Relevant equations tangential acceleration = r * α 3. The attempt at a solution The velocity equation should be the derivative of the position equation, so θ(t) = 1.5t + 9t2 → ω(t) = 1.5 + 18t Derivative of velocity equation should be acceleration so ω(t) = 1.5 + 18t → α(t) = 18 rad/s2 Now at = rα = (0.39m)(18 rad/s2) = 7.02 m/s2 Where did I go wrong?