Question

A block of $\sqrt{3}\, kg$ is attached to a string whose other end is attached to the wall. An unknown force $F$ is applied so that the string makes an angle of $30^{\circ}$ with the wall. The tension $T$ is: (Given $g =10 \,ms ^{-2}$ )

• A. $25 \,N$
• B. $15\, N$
• C. $10 \,N$
• D. $20 \,N$

Answer 1

Answer: (D)

$\theta=30^{\circ}$
$\cos \theta=\frac{\sqrt{3} g}{ T }$
$\Rightarrow \frac{\sqrt{3}}{2}=\frac{\sqrt{3} g}{ T }$
$\Rightarrow T =20\,N$