Which fundamental law forms the basis of Bernoullis equation ?

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

(density of water $=1000\; \mathrm{kgm}^{-3}$ )

Why does a flag (or ensign) flutter when there is strong wind ? Explain.

Figure shows a siphon. Choose the wrong statement:

($P_0$ = atmospheric pressure)

In old age arteries carrying blood in the human body become narrow resulting in an increase in the blood pressure. This follows from

 Consider a water jar of radius $R$ that has water filled up to height $H$ and is kept on a stand of height $h$ (see figure) . Through a hole of radius $r$  $(r << R)$ at its bottom, the water leaks out and the stream of water coming down towards the ground has a shape like a funnel as shown in the figure. If the radius of the cross-section of water stream when it hits the ground is $x.$ Then