Solving a problem in physics section 67 point 5 mechan

5. The disk rotates around a fixed axis so that the linear velocity of the points lying on the wheel rim, as a function of time, is given by the equation υ = A + Bt, where A = 0.6 m / s; B = 0.9 m / s2. Determine the radius R of the wheel if the angle α between the vectors of full acceleration and linear velocity after a period of time t = 3 s from the start of movement is 80 °.