Spherical balls of radius $ 'r'$ are falling in a viscous fluid of viscosity '$\eta$' with a velocity $ 'v'. $ The retarding viscous force acting on the spherical ball is
Inversely proportional to $ 'r'$ but directly proportional to velocity $ 'v'$
Directly proportional to both radius $ 'r' $ and velocity $ 'v'$
Inversely proportional to both radius $ 'r' $ and velocity $ 'v'$
Directly proportional to $ 'r'$ but inversely proportional to $ 'v'$
A thin square plate of side $2\ m$ is moving at the interface of two very viscous liquids of viscosities ${\eta _1} = 1$ poise and ${\eta _2} = 4$ 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 uniform velocity $10\ m/s$ horizontally then the value of minimum applied force will be ........ $N$
Give two uses of Stoke’s law.
The velocity of a small ball of mass $\mathrm{M}$ and density $d,$ when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is $\frac{\mathrm{d}}{2}$, then the viscous force acting on the ball will be :
If the terminal speed of a sphere of gold ( density $= 19.5 kg/m^3$) is $0.2\ m/s$ in a viscous liquid (density $= 1.5\ kg/m^3$ ), find the terminal speed (in $m/s$) of a sphere of silver (density $= 10.5\ kg/m^3$) of the same size in the same liquid ...... $m/s$
Water flows through a frictionless duct with a cross-section varying as shown in fig. Pressure $p$ at points along the axis is represented by