Physics 2 Marks Questions

Zero. The internal energy of the gas can change only when work is done by or on the gas. Since in this case no work is done by or on the gas, the internal energy of the gas will not change.

The atmosphere is important thermo-dynamically because:

1. The temperature difference brings wind.
2. The reflected energy from surface is prevented from escaping so that appropriate life supporting temperature exists.

p-V diagram for Carnot cycle,

The three states of a substance, namely solid, liquid and gas are called its phases. Whenever a substance can occur in several forms which are homogeneous, physically distinct, and mechanically separable from each other, the forms are called the phases of the same substance. The phases of a substance generally involve either absorption or evolution of heat.

1. Heat engine: One cannot devise a process whose only purpose is to convert heat into work.
2. Refrigerator: One cannot make heat to flow from a cold to a hot body by itself, without using any external agency.

The relative humidity in a harbour town is more than that in a town in a desert. Hence the climate of a harbour town is more temperate than that of a town in a desert.