A sphere of radius 0.25mm and of density `9000kg/m^3` falls through an oil of co-efficient of viscosity 0.2`Ns/m^2` and of density `800kg/m^3`. Find the terminal velocity of the sphere.

Using Stokes' Law show that the constant terminal velocity v of a sphere of radius r, density rho falling vertically under gravity through a viscous fluid of density sigma and co-efficient of viscosity eta is given by- v = (2/9).[{r^2g(rho - sigma)}/eta]

Oil of density 800 kg/m^3 is flowing through a horizontal pipe line. At two points separated by a distance of 1km pressure difference is 5 N/m^3 . Calculate the change in KE per kg of the oil flowing at these points.

In Millikan’s oil drop experiment, what is the terminal speed of an uncharged drop of radius 2.0 xx 10^-5m and density 1.2 xx 10^3 kg m^-3 ? Take the viscosity of air at the temperature of the experiment to be 1.8 xx 10^-5 Pa s. How much is the viscous force on the drop at that speed? Neglect buoyancy of the drop due to air.

Determine the radius of a drop of water falling through air, if it covers 4.1 cm in 4 seconds with a uniform velocity.[density of air 0.001293 g cm^-3 , viscosity of air = 1.8xx10^-4 poise]

A 1kg partical moving with a velocity 5m/s makes an elastic head on collison with a 2kg partical initially at rest. Find the final velocity of each partical .

A current of 10 ampere passes through a wire having cross-sectional area 1mm^2 . The number of free electron peer 1m^3 of the conductor is 10^(28) . Find the drift velocity of electron.

A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 m s-^1 ?