Question

A solid weighs 200N in air, 150N in water and 170N in a liquid. Find relative density of solid, relative density of liquid and density of liquid in Sl system.

Answer 1

Answer:

$\rho_{s} = 4$

$\rho_{l} = 0.6$

$\rho{liq} = 600 kg/m^{3}$

Given:

Weight of solid in air, $w_{sa} = 200 N$

Weight of solid in water, $w_{sw} = 150 N$

Weight of solid in liquid, $w_{sl} = 170 N$

Solution:

Calculation of:

1. Relative density of solid, $\rho_{s}$

$\rho_{s} = \frac{w_{sa}}{w_{sa} - w_{sw}}$

$\rho_{s} = \frac{200}{200 - 150} = 4$

2. Relative density of liquid, $\rho_{l}$

$\rho_{l} = \frac{w_{sa} - w_{sl}}{w_{sa} - w_{sw}}$

$\rho_{l} = \frac{200 - 170}{200 - 150} = 0.6$

3. Density of liquid in S.I units:

Also, we know:

$\rho{l} = \frac{\rho_{liq}}{\rho_{w}}$

where

$= {\rho_{liq}}$ = density of liquid

$= {\rho_{w}} = 1000 kg/m^{3}$ = density of water

Now, from the above formula:

$0.6 = \frac{\rho_{liq}}{1000}$

$\rho{liq} = 600 kg/m^{3}$