Question

End $A$ of the bar $AB$ figure rests on a frictionless horizontal surface and end $B$ is hinged. A horizontal force $\overrightarrow{F}$ $120N$ is exerted at end $A$. You can ignore the weight of the bar. What is the net force exerted by the bar in the hinge at $B$?

• A. $200N$
• B. $140N$
• C. $100N$
• D. none of these

Answer 1

The correct option is A $200N$

Let the angle between bar and surface be $\theta$.

$\sin \theta =\frac{4}{5}$

$⟹\cos \theta =\frac{3}{5}$

Force acts horizontally. The force experienced along the rbar=$\frac{F}{\cos \theta }=\frac{120}{\frac{3}{5}}=200N$

This force is exerted by bar on the hinge.