Newton's third law applied to thrust generation, the thrust equation and specific impulse, and how piston/propeller, turboprop, turbofan, turbojet, and rocket propulsion each fit a different point on the same speed-altitude-mission envelope.
Every propulsion system that has ever flown works on the same physical principle — accelerate a mass of working fluid rearward, and the reaction is a forward force on the vehicle. This module builds the thrust equation and specific impulse from that single idea, then uses both to explain why a propeller, a turbofan, a turbojet, and a rocket look and perform so differently: each is simply pursuing a different point on the trade-off between accelerating a large mass flow gently or a small mass flow violently.
By the end of this module you should be able to explain why a rocket needs no atmosphere to push against, why propeller efficiency collapses well below Mach 1, and why a turbofan's bypass air makes it a deliberate hybrid between the two — the exact framework Module 6's jet-engine content and Module 7's rocket-propulsion content each build on directly.