The property of a liquid by which it opposes the flow of itself is called ..........

The viscous force between two liquid layers is

$A$ thin square plate of side $2\ m$ is moving at the interface of two very viscous liquids of viscosities $\eta_1 = 1 \text{ poise}$ and $\eta_2 = 4 \text{ poise}$ respectively, as shown in the figure. Assume a linear velocity distribution in each fluid. The liquids are contained between two fixed plates. $h_1 + h_2 = 3\ m$. $A$ force $F$ is required to move the square plate with a uniform velocity $10\ m/s$ horizontally. The value of the minimum applied force will be ........ $N$.

The velocity of the upper layer of water in a river is $36 \, km/h$. The shearing stress between horizontal layers of water is $10^{-3} \, N/m^2$. The depth of the river is $h$. (The coefficient of viscosity of water is $10^{-2} \, Pa \cdot s$). Find the value of $h$ in meters.

In a laminar flow,the velocity of the liquid in contact with the walls of the tube is:

$A$ 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.