Mechanical Engineering - Thermodynamics - Discussion

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There is a change in internal energy, which is a function of temperature. Hence temperature changes.

An adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings; energy is transferred only as work. The adiabatic process provides a rigorous conceptual basis for the theory used to expound the first law of thermodynamics, and as such it is a key concept in thermodynamics.

Some chemical and physical processes occur so rapidly that they may be conveniently described by the "adiabatic approximation", meaning that there is not enough time for the transfer of energy as heat to take place to or from the system.

In way of example, the adiabatic flame temperature is an idealization that uses the "adiabatic approximation" so as to provide an upper limit calculation of temperatures produced by combustion of a fuel. The adiabatic flame temperature is the temperature that would be achieved by a flame if the process of combustion took place in the absence of heat loss to the surroundings.

The given answer is wrong. Since, it is a adiabatic process there will not be any exchange of heat between system and surroundings. Then how come the temperature changes? Only the internal energy of the system changes.

An adiabatic process (by definition) is one in which there is no heat exchange into or out of the system. When heat is added to a system its temperature may or may not change.

dQ = du+dw.
0 = du+dw;
du = -dw.

Hai, I am sairam.

Temperature is a degree of measure of hotness or coldness of a body. Then how can temperature changes in constant heat (adiabatic) process?

Adiabatic process neither heat enters nor leaves. Remember that of throttling process which is also adiabatic.

Due to change in internal energy, the temperature may change.

U = (KE + PE + IE).

KE is the kinetic energy of molecules = 3/2 kT (k = Boltzmann's const. & T = temperature).

PE is the potential energy.

IE is the intramolecular energy which may also lead to a change in temperature due to molecular re orientations.

An adiabatic as no heat added then dw = 0.

dq = du+dw.
dq = 0, dw = 0.

So du = 0.

=> du = dw process the work done is zero.