An adiabatic process is one in which no heat is gained or lost by
the system. An adiabatic process may be accomplished by thermal
insulation or by making rapid changes in volume so that there is
no time for heat to be exchanged. The first law of
thermodynamics with Q=0 shows that all the change in internal
energy is in the form of work done DU = -A. When a gas expands
adiabatically it does positive work. The internal energy drops
and the temperature drops too. On the contrary, when gas is
compressed it does the negative work and the temperature rises.
Temperature is the measure of kinetic energy of chaotic motion
of the molecules. Higher temperatures correspond to more intense
motion of the gas molecules. On a microscopic level it means
that when the piston compresses a gas, the speed at which the
molecule will be reflected from the piston will be greater than
its initial speed. Therefore after reflection from the piston
the molecule of gas will receive an additional energy which will
be redistributed with time between all molecules of gas due to
their mutual collisions.
An adiabatic process is one in which no heat is gained or lost by
the system. An adiabatic process may be accomplished by thermal
insulation or by making rapid changes in volume so that there is
no time for heat to be exchanged. The first law of
thermodynamics with Q=0 shows that all the change in internal
energy is in the form of work done DU = -A. When a gas expands
adiabatically it does positive work. The internal energy drops
and the temperature drops too. On the contrary, when gas is
compressed it does the negative work and the temperature rises.
Temperature is the measure of kinetic energy of chaotic motion
of the molecules. Higher temperatures correspond to more intense
motion of the gas molecules. On a microscopic level it means
that when the piston compresses a gas, the speed at which the
molecule will be reflected from the piston will be greater than
its initial speed. Therefore after reflection from the piston
the molecule of gas will receive an additional energy which will
be redistributed with time between all molecules of gas due to
their mutual collisions.