The pressure at half the depth of a lake is $2/3$ of the pressure at its bottom. What is the depth of the lake in $m$?

Why does food cook faster in a pressure cooker?

$A$ tank of oil has a height of $4 \,m$ and a density of $850 \,kg \,m^{-3}$. The gauge pressure at the bottom of the tank is (Given: $1 \,atm = 10^5 \,Pa$,Acceleration due to gravity $g = 10 \,m \,s^{-2}$) (in $\,kPa$)

$A$ barometer tube reads $76 \ cm$ of mercury. If the tube is gradually inclined at an angle of $60^\circ$ with the vertical,keeping the open end immersed in the mercury reservoir,the length of the mercury column will be ........ $cm$.

$A$ sudden drop in the mercury level by $10 \,mm$ or more is a sign of ..........

$A$ bubble of volume $V_0$ is released from a depth $h$ in a lake. If the atmospheric pressure is $P$ and the temperature is assumed to be constant,what is the new volume of the bubble when it reaches the surface? (Density of water is $\rho$)