Adiabatic Process

Adiabatic process: NO heat exchange with surroundings (Q = 0).

Achieved by: thermal insulation OR fast process (no time for heat to flow).

First law: ΔU = −W. If gas expands (W > 0), T DROPS. Compression heats it up.

For ideal gas: PV^γ = constant, where γ = C_p/C_v.

Equivalently: TV^(γ−1) = const, or T·P^((1−γ)/γ) = const.

Adiabatic curve on PV diagram is STEEPER than isotherm (P drops faster for same V increase).

Examples: rapid compression in a diesel engine (no time for heat loss), atmospheric air parcels rising.

Adiabatic expansion is how gas in clouds cools and condenses (rising air, lower P, lower T).