The pressure of water in a water pipe when tap is opened and closed is respectively $3 \times 10^5\,N/m^2$ and $3.5 \times 10^5\,N/m^2$ . With open tap, the velocity of water flowing is ........... $m/s$

Explain with the help of Bernoulli’s principle that why does a spinning ball follows a curve path during flight ?

In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the upper and lower surfaces of the wings are $70 \mathrm{~ms}^{-1}$ and $65 \mathrm{~ms}^{-1}$ respectively. If the wing area is $2 \mathrm{~m}^2$ the lift of the wing is__________ $\mathrm{N}$.

(Given density of air $=1.2 \mathrm{~kg} \mathrm{~m}^{-3}$ )

Water flows through a frictionless duct with a cross-section varying as shown in figure. Pressure $p$ at points along the axis is represented by

A liquid flows through a horizontal tube. The velocities of the liquid in the two sections which have areas of cross-section $A_1$ and $A_2$ are $v_1$ and $v_2$ respectively. The difference in the levels of the liquid in the two vertical tubes is $h$ . The incorrect statement is

Give reason why mercury does not wet glass.