Answer
The net acceleration at point $O$ is zero.
Point $P$ is the sweet spot.
Work Step by Step
In part (a) we found that the acceleration at point $O$ due to the force is $a = \frac{F}{m}$ and this acceleration is directed to the right.
In part (c) we found that the acceleration at point $O$ due to the angular acceleration is $a = \frac{F}{m}$ and this acceleration is directed to the left.
Since these two accelerations cancel out, the net acceleration at point $O$ is zero.
Therefore, point $P$ is the sweet spot.
