Water (of density $\varrho$) flows steadily through a horizontal pipe of variable cross-section. If the pressure of water is $P$ at a point where the flow speed is $V$,then the pressure at another point where the flow speed becomes $3V$ is:

What type of fluid can be applied in Bernoulli's equation?

$A$ large cylindrical tank of cross-sectional area $1\ m^2$ is filled with water. It has a small hole at a height of $1\ m$ from the bottom. $A$ movable piston of mass $5\ kg$ is fitted on the top of the tank such that it can slide in the tank freely without friction. $A$ load of $45\ kg$ is applied on the top of the water by the piston,as shown in the figure. The value of $v$ when the piston is $7\ m$ above the bottom is $(g = 10\ m/s^2)$ ....... $m/s$

Water flows in a horizontal tube (see figure). The pressure of water changes by $700 \; Nm^{-2}$ between $A$ and $B$ where the area of cross-section are $40 \; cm^{2}$ and $20 \; cm^{2},$ respectively. Find the rate of flow of water through the tube in $cm^{3} / s$. (Density of water $= 1000 \; kgm^{-3}$)

According to Bernoulli's equation $\frac{P}{\rho g} + h + \frac{v^2}{2g} = \text{constant}$,the terms $\frac{P}{\rho g}$,$h$,and $\frac{v^2}{2g}$ are generally called respectively:

Prove Bernoulli's Principle.