$A$ metal plate of area $10^{-2} \,m^2$ rests on a layer of castor oil,$2 \times 10^{-3} \,m$ thick,whose coefficient of viscosity is $1.55 \,Ns\, m^{-2}$. The approximate horizontal force required to move the plate with a uniform speed of $3 \times 10^{-2} \,ms^{-1}$ is (in $N$)

How does the coefficient of viscosity of a liquid and a gas depend on temperature?

Write one practical use of viscosity.

$A$ cylindrical metal box whose flat surface has an area of $0.01 \ m^2$ rests on a liquid layer of $0.3 \ mm$ thickness. If upon applying a horizontal force of magnitude $\frac{1}{3} \ N$,the box slides with a constant speed of $0.09 \ m/s$,the coefficient of viscosity of the liquid is nearly:

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 $\eta = 10^{-2}\, \text{poise}$.

$A$ metal block of base area $0.2\; m^{2}$ is connected to a $0.02\; kg$ mass via a string that passes over an ideal pulley as shown in the figure. $A$ liquid film of thickness $0.6\; mm$ is placed between the block and the table. When released,the block moves to the right with a constant speed of $0.17\; m/s$. The coefficient of viscosity of the liquid is: