Question

An object weighs $50N$. Weight of water of volume equal to the volume of the object is $70N$. Find out the relative density (${\rho }_r$) of the object.

• A. ${\rho }_r=\frac{7}{5}$
• B. ${\rho }_r=\frac{5}{7}$
• C. ${\rho }_r=35$
• D. ${\rho }_r=12$

Answer 1

The correct option is B ${\rho }_r=\frac{5}{7}$

Given:
Weight of object, $w_1$$=50N$
Weight of water of volume equal to the volume of the object, $w_2=$$70N$

Relative density of the object:
${\rho }_r=\frac{\text{density of object}}{\text{density of water}}$

The volume of the object and water is same.
$\therefore$Relative density of the object:
${\rho }_r=\frac{w_1}{w_2}$
$⟹{\rho }_r=\frac{50}{70}$
$⟹{\rho }_r=\frac{5}{7}$