Adiabatic Process
Definition
A change with no heat entering or leaving the system — temperature changes come purely from work done.
Technical definition
A thermodynamic process with Q = 0 (perfectly insulated or too fast for heat exchange). For an ideal gas, PV^γ = constant, where γ = C_p/C_v. Compressing adiabatically heats the gas; expanding cools it.
Example
Pumping a bike tire: the fast compression is nearly adiabatic, which is why the pump barrel gets hot — work went in, no heat escaped.
Common confusion
‘Adiabatic’ means no heat transfer, not constant temperature — that is isothermal. Adiabatic compression heats things up; students often conflate the two ‘special’ processes.