Question

A body of mass $m$ is suspended by a string of length ${}^{\prime }{l}^{\prime }$ and pulled to a side through horizontal distance ${}^{\prime }{r}^{\prime }$ by means of horizontal force. Then the tension in the string is

• A. $\frac{mg\sqrt{l^2-r^2}}{l}$
• B. $\frac{mgr}{l}$
• C. $\frac{mgl}{r}$
• D. $\frac{mgl}{\sqrt{l^2-r^2}}$

Answer 1

The correct option is D $\frac{mgl}{\sqrt{l^2-r^2}}$

See the image:
$Tsin\theta =mg$
$sin\theta =\frac{\sqrt{l^2-r^2}}{l}$
$T=\frac{mgl}{\sqrt{l^2-r^2}}$