The density of the atmosphere at sea level is $1.29 \; kg/m^3$. Assume that it does not change with altitude. Then how high (in $km$) would the atmosphere extend?

If a substance of mass $m_1$ and specific gravity $s_1$ is mixed with a substance of mass $m_2$ and specific gravity $s_2$,what is the specific gravity of the mixture?

The relative density of Kerosene is $0.8$. Find its density. (in $kg/m^3$)

Why are railway tracks laid on large-sized wooden sleepers?

$A$ $U$-tube contains water and methylated spirit separated by mercury. The mercury columns in the two arms are initially in level with $10.0 \; cm$ of water in one arm and $12.5 \; cm$ of spirit in the other. If $15.0 \; cm$ of water and spirit each are further poured into the respective arms of the tube,what is the difference in the levels (in $cm$) of mercury in the two arms? (The specific gravity of spirit is $0.8$.)

Gauge pressure is defined as: