\(\begin{array}{l}
{a_{og}} = {a_{op}} + {a_{pg}}\\
\,\,\,\,\,\,\,\, = - {a_{po}} + {a_{pg}}\\
\,\,\,\,\,\,\,\, = - \alpha r + a\\
\Rightarrow \frac{F}{M} = - \frac{{F \times r}}{{\frac{{M{r^2}}}{2}}} + a\\
\Rightarrow \frac{{3F}}{M} = a \Rightarrow F = \frac{{Ma}}{3}
\end{array}\)