Why does food cook faster in a pressure cooker?

Water stands up to height $h$ behind a dam as shown in the figure. The front view of the dam gate is also shown in the adjoining figure. The density of water is $\rho$ and the acceleration due to gravity is $g$. If the atmospheric pressure force is also considered,the point of application of the total force acting on the dam due to water above $O$ is:

Why is mercury used in a barometer?

At what speed,the velocity head of water is equal to the pressure head of $40 \, cm$ of mercury? (Given: Density of mercury = $13.6 \times 10^3 \, kg/m^3$,Density of water = $10^3 \, kg/m^3$,$g = 9.8 \, m/s^2$)

$A$ liquid boils when its vapour pressure equals

The height of a mercury barometer is $75 \ cm$ at sea level and $50 \ cm$ at the top of a hill. The ratio of the density of mercury to that of air is $10^4$. The height of the hill is ....... $km$.