Question

A uniform rod AB of mass $m$ and length $L$ is suspended by two strings C and D of negligible mass as shown in the figure. When string D is cut, the tension in string C will be

• A. $\frac{mg}{4}$
• B. $mg$
• C. $2mg$
• D. $4mg$

Answer 1

The correct option is A $\frac{mg}{4}$

From equation of motion

$mg-T=m{a}_c\&\tau =I\alpha mg\frac{l}{2}=\frac{m{l}^2}{3}\left(\frac{a_c}{\frac{l}{2}}\right)=a_c=\frac{3}{4}gmg-T=\frac{3}{4}mgT=\frac{1}{4}mg$