Question

The tension $T$ in the string shown in figure is

• A. Zero
• B. $50\text{N}$
• C. $35\sqrt{3}\text{N}$
• D. $(\sqrt{3}-1)50\text{N}$

Answer 1

The correct option is A Zero

The forces on the block will have component of its own weight down the incline plane and friction up the incline plane.

$mg\sin \theta =10\left(10\right)\sin {30}^{\circ }=50\text{N}$

Frictional force $=\mu mg\cos \theta =\left(0.7\right)\left(10\right)\left(10\right)\frac{\sqrt{3}}{2}=35\sqrt{3}\text{N}>\text{50 N}$
Frictional force is sufficient to oppose the cause of motion.
Hence, tension will be zero.