Question

A boy has $60kg$ weight, He wants to swim in a river with the help of a wooden log. If relative density of wood is $0.6$, what is the minimum volume of wooden log?
(density of river water is $1000kg/m^3$)

• A. $0.66m^3$
• B. $150m^3$
• C. $\frac{3}{1}{m}^3$
• D. $\frac{3}{20}{m}^3$

Answer 1

The correct option is D $\frac{3}{20}{m}^3$

Archimedes principle states that weight of body displaced by liquid = upthrust.

$60\times g+V\times 0.6\times {10}^3\times g=V\times 1000g$

$60+600V=1000V$

$V=\frac{60}{400}=\frac{3}{20}{m}^3$

where, $V$ is the volume of wooden log.