A particle moves along an arc of a circle of radius R according to the law l = α sin ωt, where l is the displacement from the initial position measured along the arc, and α and ω are constants. Assuming R = 1.00 m, α = 0.80 m, and ω = 2.00 rad /s, find:
(a) The magnitude of the total acceleration of the particle at the points l = 0 and l = ± a;
(b) The minimum value of the total acceleration wmin and the corresponding displacement lm.