2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/85190We investigate the nonequilibrium steady-state thermodynamics of single Brownian macromolecules with inertia under feedback control in isothermal ambient fluid. With the control being represented by a velocity-dependent external force, we find such open systems can have a negative entropy production rate and we develop a mesoscopic theory consistent with the second law. We propose an equilibrium condition and define a class of external forces, which includes a transverse Lorentz force, leading to equilibrium.10 pages, 1 figureClassical PhysicsGeneral Physicstext