The volume of an air bubble is doubled as it rises from the bottom of lake to its surface. The atmospheric pressure is $75 \,cm$ of mercury. The ratio of density of mercury to that of lake water is $\frac{40}{3}$. The depth of the lake in metre is .........
$10$
$15$
$20$
$25$
Mention two instruments which measure the atmospheric pressure.
A barometer kept in a stationary elevator reads $76 cm$. If the elevator starts accelerating up the reading will be
The diagram shows a simple mercury barometer.Which of the following does not cause the height of the mercury column to vary ?
The pressure at the bottom of a water tank is $4 P$. where $P$ is atmospheric pressure. If water is drawn out till the water level decreases by $\frac{3}{5}^{th}$ , then pressure at the bottom of the tank is .........
Pressure at the bottom of a tank of water is $3P$, where $P$ is atmospheric pressure. If water is drawn out till the level of water is lowered by one fifth, then the pressure at the bottom of the tank is