Physic Labs

Problem 2

A reversible Carnot engine operates between large reservoirs at constant absolute temperatures Th>Tc>0T_h>T_c>0. Each cycle absorbs heat Qh>0Q_h>0 from the hot reservoir and rejects heat of magnitude Qc>0Q_c>0 to the cold reservoir; there are no other energy transfers. (a) Relate the heats to reservoir temperatures. (b) Find useful work per cycle. (c) Find efficiency and consider the limit TcoThT_c o T_h. Keep the sign convention consistent and use appropriate SI units throughout. Each part builds on intermediate results from the preceding part; apply a physical relation only where the stated model assumptions hold. Finally compare the answers with the initial conditions, expected trends, and an independent check when available.
W=Qh−QcW=Q_h-Q_c
problems.proof.analysis

Solve the algebraic expression and retain the solution consistent with the physical domain. Checking units helps catch algebraic errors.

problems.proof.pitfall. Reversibility fixes the reservoir entropy balance; do not choose rejected heat independently.