How coefficient of liquid and gas depend on temperature ?
Coefficient of viscosity of a liquid decreases while that of a gas increase, with increasing temperature. This is because the viscosity in gases depend upon the molecular momentum exchange while in liquid it depends upon the cohesive force.
$\Rightarrow$ In gas molecular momentum increases due to increase of temperature, hence viscosity increases.
$\Rightarrow$ In the liquid cohesive force decreases with temperature increase, hence viscosity decreases.
A plastic circular disc of radius $R$ is placed on a thin oil film, spread over a flat horizontal surface. The torque required to spin the disc about its central vertical axis with a constant angular velocity is proportional to
Give two uses of Stoke’s law.
A water drop of radius $1\,\mu m$ falls in a situation where the effect of buoyant force is negligible. Coefficient of viscosity of air is $1.8 \times 10^{-5}\,Nsm ^{-2}$ and its density is negligible as compared to that of water $10^{6}\,gm ^{-3}$. Terminal velocity of the water drop is________ $\times 10^{-6}\,ms ^{-1}$
(Take acceleration due to gravity $=10\,ms ^{-2}$ )
The average mass of rain drops is $3.0\times10^{-5}\, kg$ and their avarage terminal velocity is $9\, m/s$. Calculate the energy transferred by rain to each square metre of the surface at a place which receives $100\, cm$ of rain in a year
A small sphere of radius $r$ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to