Question

A fisherman hooks an old log of wood of weight 12N and volume 1000 $c{m}^3$. He pulls the log half way out of water. The tension in the string at this instant is

• A. 12 N
• B. 8 N
• C. 10 N
• D. 7 N

Answer 1

The correct option is D

7 N

Forces acting on log will be,

mg downwards

and buoyant force,

$\left(V_{im}\right){\rho }_{liquid}g=\left(\frac{V}{2}\right){\rho }_{water}gupwards.$

Tension in string is,

$T=Mg-\left(\frac{V}{2}\right){\rho }_{water}g=7N$