Question

A square plate is hinged as shown in figure and it is held stationary by means of a light thread as shown in figure. Then find out the force exerted by the hinge.

• A. $0$
• B. $mg$
• C. $mg-T$
• D. $mg+T$

Answer 1

The correct option is A $0$


Let $N$ be the force exerted by the hinge.
From FBD of square plate we can see that tension $T$ and weight $mg$ have same line of action.
Under equilibrium condition,
${\tau }_{hinge}=0$
$\Rightarrow T=mg$ ... $\left(1\right)$
Also,
$F_{net}=0$
$\Rightarrow N+T=mg$
$\Rightarrow N=0$ Using $\left(1\right)$
So, the force exerted by the hinge, i.e$N=0$.