Question

A block of mass $3\text{kg}$ is at rest on a rough inclined plane as shown in the figure. The magnitude of net force exerted by the surface on the block will be $(g=10{\text{m/s}}^2)$

• A. $26\text{N}$
• B. $19.5\text{N}$
• C. $10\text{N}$
• D. $30\text{N}$

Answer 1

The correct option is D $30\text{N}$

As the block is at equilibrium
$N=mg\cos {30}^{\circ }=15\sqrt{3}N$
$f=mg\sin {30}^{\circ }=15N$


$\therefore$ Total contact force $=\sqrt{{\left(15\sqrt{3}\right)}^2+(15{)}^2}=30\text{N}$