Water is flowing steadily in a river. $A$ and $B$ are two layers of water at heights $40 \ cm$ and $90 \ cm$ from the bottom. The velocity of layer $A$ is $12 \ cm/s$. If the velocity of the water at the bottom is $0$,what is the velocity of layer $B$ (in $cm/s$)?

$A$ river $10\,m$ deep is flowing at $5\,m/s$. The shearing stress between horizontal layers of the river is :- $(\eta = 10^{-3}\,SI\,unit)$

Water is flowing on a horizontal fixed surface,such that its flow velocity varies with $y$ (vertical direction) as $v = k \left( \frac{2y^2}{a^2} - \frac{y^3}{a^3} \right)$. If the coefficient of viscosity for water is $\eta$,what will be the shear stress between the layers of water at $y = a$?

When stirring with a spoon is stopped in milk,it comes to rest after some time. Why?

$A$ cubical block of side $a$ and density $\rho$ slides over a fixed inclined plane with constant velocity $v$. There is a thin film of viscous fluid of thickness $t$ between the plane and the block. If the angle of inclination is $37^{\circ}$,then the coefficient of viscosity of the thin film will be:

$A$ metal cube of side $10 \,cm$ rests on a film of a liquid of thickness $0.2 \,mm$. If upon applying a horizontal force $\overrightarrow{F}$ of magnitude $0.1 \,N$ the cube slides with a constant speed of $0.08 \,m/s$, then the coefficient of viscosity is