The rocket equation describes the relationship between the velocity change (), the effective exhaust velocity (), and the initial and final masses of a rocket. For liquid propellant rockets, the rocket equation is expressed as:
Where:
- is the change in velocity of the rocket (in meters per second, m/s).
- is the specific impulse of the rocket engine (in seconds, s).
- is the acceleration due to gravity at the Earth’s surface (approximately 9.81 m/s2).
- is the initial mass of the rocket (including propellant and structure, in kilograms, kg).
- is the final mass of the rocket (after propellant burnout, in kilograms, kg).