The relative velocity of two consecutive layers is $8 \ cm/s$. If the perpendicular distance between the layers is $0.1 \ cm$,then the velocity gradient will be ......... $s^{-1}$.

$A$ 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. Then the coefficient of viscosity of the thin film will be

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

Explain the velocity gradient and the coefficient of viscosity,and provide their units.

The coefficient of viscosity of an ideal fluid is

The speed of the water in a river is $V$ near the surface. If the coefficient of viscosity of water is $\eta$ and the depth of the river is $H$, then the shearing stress between the horizontal layers of water is