$A$ container of height $10 \, cm$ is filled with water. There is a hole at the bottom. Find the pressure difference between points at the top and the bottom.

The pressure at the bottom of a liquid tank is not proportional to the

Explain how an open-ended tube manometer measures pressure.

$A$ barometer kept in an elevator reads $76 \, cm$ when the elevator is accelerating upwards. The most likely pressure inside the elevator (in $cm$ of $Hg$) is ........

$A$ manometer reads the pressure of a gas in an enclosure as shown in Figure $(a)$. When a pump removes some of the gas,the manometer reads as in Figure $(b)$. The liquid used in the manometers is mercury and the atmospheric pressure is $76 \; cm$ of mercury.
$(a)$ Give the absolute and gauge pressure of the gas in the enclosure for cases $(a)$ and $(b)$,in units of $cm$ of mercury.
$(b)$ How would the levels change in case $(b)$ if $13.6 \; cm$ of water (immiscible with mercury) are poured into the right limb of the manometer? (Ignore the small change in the volume of the gas).

When an airplane flies at a higher altitude,it is not advisable to keep a fountain pen in one's pocket. Why?