Rocket motors are used both in space vehicles and in offensive weapons such as missiles. The propulsion system in most space vehicles consists of rocket engines powered by chemical propellants. These are called rocket propellants. Propellants are combustible compounds which on ignition undergo rapid combustion to release large quantities of hot gases. A propellant is Combination of an oxidiser and a fuel .
Working of propellant: When a propellant is ignited, it burns to produce a large quantity of gases. These gases then come out through the nozzle of the rocket motor . The passage of gases through the nozzle of the rocket motor provides the necessary thrust for the rocket to the move forward according to the newton's third law of motion. Some examples of propellant are hydrazine, liquid hydrogen and polyurethane.