Question

A U-tube having horizontal arm of length $20cm,$ has uniform cross-sectional area $=1c{m}^2$. It is filled with water of volume $60cc$ What volume of a liquid of density $4g/cc$ should be poured from one side into the U-tube so that no water is left in the horizontal arm of the tube?

• A. $60c{m}^2$
• B. $45c{m}^2$
• C. $55c{m}^2$
• D. $35c{m}^2$

Answer 1

The correct option is D $35c{m}^2$

${\rho }_{1}g{h}_1={\rho }_{2}g{h}_2$
$\therefore$ $\left(4\right)\left(g\right)\left(x\right)=\left(1\right)\left(g\right)\left(60\right)$
or $x=15cm$
Total volume of liquid $=(20+15)cm$${}^2$$=35cm$${}^2$