Physics 1 Marks Question

Yes, by reducing pressure on water, boiling point of water can be brought down to room temperature.

Leaking of air is adiabatic expansion and adiabatic expansion produces cooling.

An indicator diagram is a graphical representation of the state of a system with the help of two thermodynamic variables (generally pressure and volume). Work done by a system is numerically equal to area under the P-V indicator diagram.

Yes, by doing work to change its volume (decrease).

Variation of specific heat of water with temperature:

No.

No, we cannot design an ideal Carnot engine in practice.

Change in pressure will be more than 3 times the initial pressure.

The mechanical work can be completely converted into heat, but heat extracted from somebody cannot be completely converted into useful work.

Freon (CCI₂F₂ → dichloro fluoromethane).

According to second law, it is not possible to cool a system cooler than its surroundings without doing work on it.

It leads us to the concept of temperature.

This is because in the cloudy night, heat radiated out from earth is reflected by the clouds back to earth.
Hence, temperature of the earth does not fall.

It is a device that helps in maintaining a constant temperature. It consists of a bi-metallic strip which comprises of two thin strips of different materials (such as brass and invar) welded together along their lengths. On heating, this combination bends into an arc. It happens because brass has a higher coefficient of expansion than invar.

The efficiency of a Carnot engine can be 100% if the temperature of sink is absolute zero.

The statement may not be true always because heat content of a body depends on mass of body, its specific heat and temperature.

No, Camphor.

To make the vehicle to move at constant speed, constantly the brake has to be applied to work against the available energy. So, it gets heated up.

No, a ship cannot be moved in a sea by the use of the energy of sea water because refrigerator is against the second law of thermodynamics.

Second law of thermodynamics, which says that 100% conversion of heat into work is impossible.

It is based on the fact that the change in volume of mercury is nearly proportional to the change in temperature.

Yes, in an adiabatic process the temperature of an isolated system changes. It increases when the gas is compressed adiabatically.

The efficiency is independent of the nature of the working substance.

Yes.

According to first law of thermodynamics when some quantity of heat (dQ) is supplied to a system capable of doing external work, then quantity of heat absorbed by the system (dQ) is equal to sum of increase in internal energy of system (dU) due to rise in temperature and external work done by system (dW) in expansion i.e.
dQ = dU + dW

Heat lost by a body is equal to heat gained by the other when they are mixed.