What are the direction of acceleration at various point during the oscialltion of a simple pendulum?

Explanation

During the oscillation of a simple pendulum, the direction of acceleration at differenct points is different and is shown in figure , by arrow heads.
At the extreme positions A and B, for the angular dispacement of the bob `'theta'`, the radial component of the weight mg, i.e., `mg cos theta ` balances the tension in the string. The tangential component of weight me, i.e., `mg sin theta` provides the restoring force and hence produces acceleration tangential to the arc AB, directed towards the mean position.
At any other position, i.e., at C or D, the bob is moving along a circular path. There is force `= T-mg cos theta^(')` , providing the contripetal force. The net force, which is the resultant of centripetal force and tangential force acts at an angle shown in figure. , 1 by arrowhead, which gives the direction of acceleration.
At the mean position O, the angular displacement of the bob becomes zero, i.e., `theta=0^(@)`, therefore , the tangential component mg` sin theta` becomes zero. Here the effective force on the bob is only due to radial component of the weight. Therefore, the direction of acceleration is directed towards the point of suspension S of the string.