The speed of a particle v in uniform circular motion is its angular speed times the radius of the circle A.
i.e, v =A
now the velocity of the projection particle p' at time t is
v(t) = -Asin(t+) where the negative sign indicates that v(t) has a direction opposite to the positive direction of x-axis.
differentiating teh equation w.rt to time we get acceleration of moving particle