There is a $1\, mm$ thick layer of glycerine between a flat plate of area $100\, cm^2$ and a big plate. If the coefficient of viscosity of glycerine is $1.0\, kg/(m\cdot s)$,then the force required to move the plate with a velocity of $7\, cm/s$ is $.......\, N$.

Viscous drag force depends on ...........

There is a $1$ $mm$ thick layer of glycerine between a flat plate of area $100$ $cm^2$ and a big fixed plate. If the coefficient of viscosity of glycerine is $1.0$ $kg/(m \cdot s)$,then what force in $N$ is required to move the plate with a velocity of $7$ $cm/s$?

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

$A$ flat plate of area $0.1 \,m^2$ is placed on a flat surface and is separated from it by a film of oil $10^{-5} \,m$ thick whose coefficient of viscosity is $1.5 \,N \cdot s \cdot m^{-2}$. The force required to cause the plate to slide on the surface at a constant speed of $1 \,mm \cdot s^{-1}$ is ............ $N$.

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