Sparks fly off tangentially when a knife is rubbed on a hard rotating dix. How can account for .

The discs of moments of inertia I_1 and I_2 about their respective axis (normal to the disc and passing through the centre), and rotating with agnular speeds omega_1 and omega_2 are brought into contact face to face with their axis of rotation coincident. Show that the kinetic energy of the combined system is less than the sum of the initial kinetic energies of the two discs. How do you account for this loss in energy ? Take omega_1 ne omega_2 .

When two identical spheres collide obliquely with one of them initialyly at rest,then fly off making an angle theta .What is the value of angle theta if the collision is elastic?

The following curve is obtained when molar conductivty, Lambda_m is plotted against the square rot of concentration, C^(1//2) along y and x axis respectively for the two electrolytes X and Y. How do you account for the increase in Lambda_m for the electolytes X and Y with dilution?

Read the given passage and answers following questions : The cleansing action of soap is due to emulsification and micelle formation. Soaps are basically sodium and potassium salts of long chain fatty acids, R-COO- Na^(+) . The end of the molecule to which the sodium is attached is polar in nature, while the alkyl-end is non-polar. Thus, a soap molecule contains a hydrophilic (polar) and a hydrophobic (nonpolar) part. When soap is added to water containing dirt, the soap molecules surround the dirt particles in such a manner that their hydrophobic parts get attached to the dirt molecule and the hydrophilic parts point away from the dirt molecule. This is known as micelle formation. Thus, we can say that the polar group dissolves in water while the non-polar group dissolves in the dirt particle. Now, as these micelles are negatively charged, they do not coalesce and a stable emulsion is formed. How many parts of soaps exist ?

A spark passes though air when the potential gradient is 3xx10^(6) volts per metre what must be the radious of an isoated metal sphere which can be changed to a potentiial of 3 million voilts before there are sparks in the air?

A committee of 7 has to be formed from 9 boys and 4 girls. In how many ways can this be done when the committee consists of : at least three girls.

In defining electric field due to a point charge, the test charge has to be vanishingly small. How this condition can be justified, when we know that charge less than the on an electron or a proton is not possible?

Earth can be thought of as a sphere of radius 6400 km.Any object (or a person) is pewrforming circular motion around the axis of the earth due to the earth rotation (period 1 day). What is acceleration of object on the surface of the earth (at equator) towards its centre? What is it at latitude theta ? How does these acceleration compare with g = 9.8 m//s^(2) ?