Write one practical use of viscosity.

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

What is the value of the shear modulus of sulfuric acid?

As the temperature of water increases,its viscosity

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 $7$ $cm/s$?

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