u/Evening_Serve_1338

Hi everyone, I’m curious about the fundamental physics of rocket propulsion.

According to Newton's Third Law, we often say 'for every action, there is an equal and opposite reaction.' In many textbooks, the 'reaction force' that pushes the rocket upward is described as the gas molecules pushing against the internal walls/nozzle of the engine.

My question is: Is it more accurate to view thrust as the pressure exerted on the engine's internal structure, or is it strictly the conservation of momentum from the high-velocity exhaust gases? I’d love to hear a more technical breakdown of how this force is actually transferred to the rocket's frame.