In an isolated system undergoing an adiabatic process, what remains constant?
**Cyclic process** system returns to initial state, ΔU=0 over cycle, net work W_net = area enclosed in P-V diagram, Q_net = W_net from first law ΔU= Q - W =0 => Q_net = W_net, clockwise cycle work done by system positive, counterclockwise work done on system negative, efficiency η = W_net/Q_in. In an isolated adiabatic system ( Δ Q = 0 ), no heat or matter is exchanged. The First Law ( Δ U = -Δ W ) applies, but total energy (internal energy) is conserved if no external work is done ( Δ W = 0 ), making total energy constant. Using first law
Ref: NCERT > Physics Book > Thermodynamics > Cyclic Processes and Reversibility Concepts