$A$ liquid is kept in a cylindrical vessel. When the vessel is rotated about its axis,the liquid rises at its sides. If the radius of the vessel is $0.05\, m$ and the speed of rotation is $2$ revolutions per second,the difference in the heights of the liquid at the centre and at the sides of the vessel will be ...... $cm$. (Take $g = 10\, ms^{-2}$ and $\pi^2 = 10$)

Explain why bullets of a gun are cylindrical in shape.

The temperature of an air bubble while rising from the bottom to the surface of a lake remains constant, but its diameter is doubled. If the pressure on the surface is $h$ meters of mercury column and the relative density of mercury is $\rho$, then the depth of the lake is: (in $\rho h$)

Why can liquids flow?

Fill in the blanks:
$(i)$ The cohesive force between the molecules of liquid is more than the adhesive force between the molecules of the plate, then the angle of contact obtained is ...... (acute/obtuse) and the free surface has a shape of ...... (concave/convex).
$(ii)$ The cohesive force between the molecules of liquid is less than the adhesive force between the molecules of the plate, then the angle of contact obtained is ...... (acute/obtuse) and the free surface has a shape of ...... (concave/convex).
$(iii)$ $A$ large pressure is exerted on the surface of a liquid having a shape of .......... (concave/convex).

$A$ glass tube of uniform cross-section is filled with water and mounted on a rotatable shaft as shown in the figure. If the tube is rotated with a constant angular velocity $\omega$,then: