Work Done In Thermodynamic Cycle — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Work Done In Thermodynamic Cycle This formula applies specifically when a thermodynamic system undergoes a complete cycle, returning to its initial state (e.g., in an engine or refrigerator). Start with the First Law of Thermodynamics: U = Q - W. For a complete cycle, the change in internal energy is zero: U = 0. Therefore, the net work done (W) equals the net heat absorbed (Q): W = Q. The net heat absorbed (Q) is the difference between heat input (Q 1) and heat output (Q 2): W = Q 1 - Q 2. The system must undergo a closed cycle (initial state = final state). Q 1 must represent heat absorbed by the system (Input). Q 2 must represent heat rejected by the system (Output). Confusing the total work done (W) with the net heat absorbed (Q). Assuming work is always positive (it can be negative if the system is doing work on the surroundings). Forgetting that for a complete cycle, the change in internal energy ( U) must be zero.