Answer
$F_a = 300~N$
Work Step by Step
When $\frac{y}{L} = 0$, the force $F_a$ is applied at the location of the hinge.
Since $T = 0$ when $\frac{y}{L} = 0$, then the force $F_h$ is equal and opposite to the force $F_a$.
Note that $F_h = 300~N$ when $\frac{y}{L} = 0$
Therefore, $F_a = 300~N$
