Question

Explain the characteristics of rocket propellants.

Answer 1

Hint: A rocket can be defined as a long circular device which is actually launched into the air. A propellant, on the other hand, is a combination of fuel as well as oxidizer.

Complete step by step answer:
Rocket motors are employed not only in space vehicles but also in offensive weapons like missiles. In most of the space vehicles, the propulsion system comprises the rocket engines which are powered by chemical propellants. Thus, these propellants are known as rocket propellants. These rocket propellants are basically combustible compounds inclusive of fuels such as kerosene, hydrazine and its derivatives, liquid hydrogen, alcohol and oxidizers such as nitric acid, liquid fluorine, nitrogen tetroxide and liquid oxygen. These propellants undergo rapid combustion on ignition to release a large quantity of hot gases.
Description of the working of propellant: On ignition, a propellant produces a large amount of gases. These gases ooze out of a nozzle in a rocket motor. This passage of gases via nozzle supplies the necessary thrust to the rocket due to which it moves forward (can be explained by Newton's third law of motion).

Note:
Chemical rockets can be grouped together according to the phase (solid, liquid, gas, hybrid). Solid rockets utilise propellant that is present in the solid phase, liquid fuelled rockets utilise propellant in the liquid phase, gas fuelled rockets utilise propellant in the gaseous phase, and finally hybrid rockets utilise a combination of solid as well as liquid or gas phase propellants. Solid fuelled rockets typically have high thrust, short burn time, lesser specific impulse, and possess a higher mass compared to liquid fuelled rockets, and moreover, they cannot be stopped once ignited.