If the ratio of diameters, lengths and Young's modulus of steel and copper wires shown in the figure are p, q and s respectively, then the corresponding ratio of increase in their lengths would be

A fluid is in streamline flow across a horizontal pipe of variable area of cross section. For this which of the following statements is correct?

The molar specific heats of an ideal gas at constant pressure and volume are denoted by C_p and C_v, respectively. If  $$\gamma $$ = $${{{C_p}} \over {{C_v}}}$$ and R is the universal gas constant, then C_v is equal to

A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using