Question

Relative density of a metal may be found with the help of spring balance. In air the spring balance reads $(5.00\pm 0.05)$ N and in water it reads $(4.00\pm 0.05)$N. Relative density would be:

• A. $(5.00\pm 0.05)N$
• B. $(5.00\pm$ 11%)
• C. $(5.00\pm 0.10)$
• D. $(5.00\pm$ 6%)

Answer 1

The correct option is D $(5.00\pm$ 6%)

Relative density $=\frac{\text{Weight of body in air}}{\text{Loss of weight in water}}$$=\frac{5.00}{5.00-4.00}=\frac{5.00}{1.00}$

$\frac{\Delta \rho }{\rho }\times 100=(\frac{0.05}{5.00}+\frac{0.05}{1.00})\times 100$
$=(0.01+0.05)\times 100$
$=0.06\times 100$

$=6$%
$\therefore$ Relative density $=5.00\pm$ 6%