Question

A rod OA of mass $4kg$ is held in horizontal position by a massless string AB as shown in figure. Length of the rod is $2m$. Find net force exerted by hinge on the rod. (g= $10m/s^2$)

• A. $23.1N$
• B. $20N$
• C. $17.32N$
• D. $14.14N$

Answer 1

The correct option is A $23.1N$

Given,

Mass of the rod $m$ = $4kg$

Let tension due to the string be $T$ acting at an angle of $60$°.

On resolving and balancing forces , we can calculate force acting by hinge on rod.

Let $N$ be the force acting by hinge along the rod.

Hence,

$T\left(sin\theta \right)=mg$

and

$T\left(cos\theta \right)=N$

On solving and putting $\theta$ $=60°$,

We have,

$N$$=40/1.73N=23.1N$