Question

In the arrangement, the minimum value of tension in the string to prevent it from sliding down is :

• A. $6N$
• B. $8N$
• C. $10.8N$
• D. Zero

Answer 1

The correct option is D Zero

Limiting friction along the plane upward
$={\mu }_{s}mgcos\theta$
$=0.8\times 1\times 10\times \cos {37}^{\circ }$
$=0.8\times 10\times \frac{4}{5}$
$=6.4N$
Force responsible for downward motion
$=mg\sin \theta$
$=1\times 10\times \sin {37}^{\circ }$
$=1\times 10\times \frac{3}{5}$
$=6N$
As, downward force $<$ limiting friction.
So, frictional force $=$ downward force.
Hence, tension in string is zero.