The Tsiolkovsky rocket equation and why it makes staging necessary, liquid versus solid propellants, specific impulse for rockets, and thrust chamber and nozzle basics.
The rocket equation, Δv = Isp·g0·ln(m0/mf), is the single relationship nearly every rocket mission-design decision traces back to — and its logarithmic form is exactly why staging exists at all. This module builds that equation from Module 5's thrust and specific-impulse foundation, then works through what actually distinguishes liquid propellants from solid propellants, and how a converging-diverging nozzle converts a rocket's chamber pressure into the supersonic exhaust velocity that produces thrust.
By the end of this module you should be able to explain why no orbital launch vehicle has ever flown as a single stage, why liquid engines can throttle and restart while solid motors cannot, and why a fixed-geometry nozzle's Isp differs between sea level and vacuum — each traced back to the same physics established here.