Question

A block of steel of size $5\times 5\times 5c{m}^3$ is weighed in water. If relative density of steel is $7$, its apparent weight is

• A. $6\times 5\times 5\times 5gwt$
• B. $4\times 4\times 4\times 7gwt$
• C. $5\times 5\times 5\times 7gwt$
• D. $4\times 4\times 4\times 6gwt$

Answer 1

Answer: (A)

Apparent weight $={\rho }_s{v}_{b}g-{\rho }_w{v}_{b}g$
$=v_{b}g\left({\rho }_s-{\rho }_w\right)$
$=5\times 5\times 5\times g\times (7-1)$
$[{\rho }_w=1{\rho }_s=7\text{(given)}$
$=6\times 5\times 5\times 5\times gwt$
Where, ${\rho }_s$ - density of steel
${\rho }_w$-density of water
$v_b$ - volume of block
(side $\times$ side $\times$ side)