The velocity of water in a river is $18\, km/h$ near the surface. If the river is $5\, m$ deep,find the shearing stress between the horizontal layers of water. The coefficient of viscosity of water is $\eta = 10^{-2}\, \text{poise}$.

$A$ square plate of side $0.1 \, m$ moves over another plate with a velocity of $0.1 \, m/s$ in a liquid of viscosity $0.01 \, poise$. If the viscous force acting is $0.002 \, N$,what is the distance between the two plates (in $, m$)?

$A$ thin plate is placed between two fixed plates,separating two liquids with coefficients of viscosity $\eta$ and $4\eta$,as shown in the figure. If the plate is to be pulled by applying the minimum force,then the ratio $\frac{d_2}{d_1}$ is:

$A$ 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

$A$ 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 ............ $N$.

$A$ metal block of area $0.10 \; m^2$ is connected to a $0.010 \; kg$ mass via a string that passes over an ideal pulley (considered massless and frictionless),as shown in the figure. $A$ liquid with a film thickness of $0.30 \; mm$ is placed between the block and the table. When released,the block moves to the right with a constant speed of $0.085 \; m s^{-1}$. Find the coefficient of viscosity of the liquid.