The value of $g $ at a place decreases by $ 2\%.$ The barometric height of mercury

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 .........

$9\  kg$ of mercury is poured into a glass $U-tube$ with inner diameter of $1.2 \ cm$. The mercury can flow without friction within the tube.  the oscillation period ......... $\sec$. Density of mercury = $13.6 × 10^3\  kg/m^3$. 

What is the pressure on a swimmer $20 \,m$ below the surface of water ........ $atm$

Water is filled up to a height $h$ in a beaker of radius $R$ as shown in the figure. The density of water is $\rho$, the surface tension of water is $T$ and the atmospheric pressure is $P_0$. Consider a vertical section $A B C D$ of the water column through a diameter of the beaker. The force on water on one side of this section by water on the other side of this section has magnitude

A light cylindrical vessel is kept on a horizontal surface. Area of base is A. A hole of crosssectional area $'a'$ is made just at its bottom side. The minimum coefficient of friction necessary to prevent sliding the vessel due to the impact force of the emerging liquid is $(a\,<\,<\,A)$