$A$ manometer connected to a closed tap reads $4.5 \times 10^5 \text{ Pa}$. When the tap is opened,the reading of the manometer falls to $4 \times 10^5 \text{ Pa}$. The velocity of the flow of water is ........ $m/s$.

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

Why do two rowing boats moving parallel to each other come closer (attract) to each other?

Water is flowing in streamline motion through a horizontal tube. The pressure at a point in the tube is $p$ where the velocity of flow is $v$. At another point, where the pressure is $p/2$, the velocity of flow is (density of water $= \rho$)

Air is blowing across the horizontal wings of an aeroplane in such a way that its speeds below and above the wings are $90\, m/s$ and $120\, m/s$ respectively. If the density of air is $1.3\, kg/m^3$,then the pressure difference between the lower and upper sides of the wings will be ........ $N/m^2$.

The reading of a pressure meter attached to a closed pipe is $4.5 \times 10^4 \ N/m^2$. On opening the valve,water starts flowing and the reading of the pressure meter falls to $2.0 \times 10^4 \ N/m^2$. The velocity of water is found to be $\sqrt{V} \ m/s$. The value of $V$ is . . . . . .