The terminal velocity of a copper ball of radius $2.0 \;mm$ falling through a tank of oll at $20\,^{\circ} C$ is $6.5 \;cm s ^{-1} .$ Compute the viscosity of the oil at $20\,^{\circ} C .$ Density of oil is $1.5 \times 10^{3} \;kg m ^{-3},$ density of copper is $8.9 \times 10^{3} \;kg m ^{-3}$
$1.1 \times 10^{-1} kg m ^{-1} s ^{-1}$
$9.9 \times 10^{-1} kg m ^{-1} s ^{-1}$
$6.37 \times 10^{-2} kg m ^{-1} s ^{-1}$
$5.98 \times 10^{-1} kg m ^{-3} s ^{-1}$
On which factors terminal velocity depends ? Explain.
When a body falls in air, the resistance of air depends to a great extent on the shape of the body, $ 3 $ different shapes are given. Identify the combination of air resistances which truly represents the physical situation. (The cross sectional areas are the same).
Write $\mathrm{SI}$ and $\mathrm{CGS}$ unit of coefficient of viscosity.
What is the velocity $v$ of a metallic ball of radius $r$ falling in a tank of liquid at the instant when its acceleration is one-half that of a freely falling body ? (The densities of metal and of liquid are $\rho$ and $\sigma$ respectively, and the viscosity of the liquid is $\eta$).
How coefficient of liquid and gas depend on temperature ?