Thermodynamics Physics - Thermodynamics

Device which converts continuously heat energy into mechanical energy in a cyclic process is known as _________.

'Heat cannot itself flow from a body at lower temperature to a body at higher temperature' is a statement in consequence of ­­________________.

When state variable of a thermodynamic system do not change system is said to be in _________.

As per sign conventions, heat absorbed by a system is _________ and heat given out by a system is _________.

Is it possible to heat a body without providing heat energy? How?

What is the value of specific heat of water in S.I. units? Does it vary with temperature?

What is a thermostat? Briefly explain its principle.

How is the efficiency of a Carnot engine affected by the nature of the working substance?

Does the internal energy of an ideal gas change in an adiabatic process?

Explain why: The coolant in a chemical or a nuclear plant (i.e., the liquid used to prevent the different parts of a plant from getting too hot) should have high specific heat.

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following: Do the intermediate states of the system (before settling to the final equilibrium state) lie on its P-V-T surface?

Explain why: Air pressure in a car tyre increases during driving.

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following: What is the change in the temperature of the gas?

Explain why: The climate of a harbour town is more temperate than that of a town in a desert at the same latitude.

An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joules per second. At what rate is the internal energy increasing?

A thermodynamic system is taken from an original state to an intermediate state by the linear process shown in Fig.
Its volume is then reduced to the original value from E to F by an isobaric process. Calculate the total work done by the gas from D to E to F.

In changing the state of a gas adiabatically from an equilibrium state A to another equilibrium state B, an amount of work equal to 22.3J is done on the system. If the gas is taken from state A to B via a process in which the net heat absorbed by the system is 9.35 cal, how much is the net work done by the system in the latter case? (Take 1 cal = 4.19J)

Read the passage given below and answer the following questions from (i) to (iv). Zeroth Law of Thermodynamics states that two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other. The Zeroth Law clearly suggests that when two systems A and B, are in thermal equilibrium, there must be a physical quantity that has the same value for both. This thermodynamic variable whose value is equal for two systems in thermal equilibrium is called temperature (T). Thus, if A and B are separately in equilibrium with C, TA = TC and TB = TC. This implies that TA = TB i.e. the systems A and B are also in thermal equilibrium. Zeroth Law of Thermodynamics leads to the concept of internal energy of a system. We know that every bulk system consists of a large number of molecules. Internal energy is simply the sum of the kinetic energies and potential energies of these molecules. A certain amount of heat is supplied to the system’ or ‘a certain amount of work was done by the system its energy changes.

1. Three thermodynamic systems are at temperature of 500 c .what can we say about them?

1. Heat flows between them
2. It obeys Zeroth Law of Thermodynamics
3. Temperature of one system will increase and temperature of remaining two will decrease
4. None of these

2. Zeroth law of thermodynamics helped in the creation of which scale?

1. Temperature
2. Heat energy
3. Pressure
4. Internal energy

3. State Zeroth Law of Thermodynamics:
4. Define Internal energy of system:

Read the passage given below and answer the following questions from (i) to (v). Kelvin-Planck statement: No process is possible whose sole result is the absorption of heat from a reservoir and the complete conversion of the heat into work. Clausius statement: No process is possible whose sole result is the transfer of heat from a colder object to a hotter object. It can be proved that the two statements above are completely equivalent. A thermodynamic process is reversible if the process can be turned back such that both the system and the surroundings return to their original states, with no other change anywhere else in the universe. a reversible process is an idealized motion. A process is reversible only if it is quasi-static (system in equilibrium with the surroundings at every stage) and there are no dissipative effects. For example, a quasi-static isothermal expansion of an ideal gas in a cylinder fitted with a frictionless movable piston is a reversible process. The free expansion of a gas is irreversible. The combustion reaction of a mixture of petrol and air ignited by a spark cannot be reversed. Cooking gas leaking from a gas cylinder in the kitchen diffuses to the entire room. The diffusion process will not spontaneously reverse and bring the gas back to the cylinder. The stirring of a liquid in thermal contact with a reservoir will convert the work done into heat, increasing the internal energy of the reservoir. The process cannot be reversed exactly; otherwise it would amount to conversion of heat entirely into work, violating the Second Law of Thermodynamics. Irreversibility is a rule rather an exception in nature.

1. The diffusion process is:

1. Reversible process
2. Irreversible process

2. A quasi-static isothermal expansion of an ideal gas in a cylinder fitted with a frictionless movable piston is

1. Reversible process
2. Irreversible process

3. State Kelvin Planck statement.
4. State Clausius statement.
5. Define reversible processes and irreversible processes of thermodynamics.