When a multi-stage booster is fired into space, the mass of the booster changes as the fuel is burned during flight. Multistage boosters have retractable parts that break away the used fuel tank, one stage by the other to achieve the farthest distance away from the earth as it is being pushed down by gravity. Fuels are burned with oxygen to create an explosion. The explosion is being controlled by a chamber to produce thrust. The force that is exerted from the engine, which pressures the rocket out towards the other direction.
The force, however, would also have to carry the whole mass of the booster. The weight of the booster can decrease significantly by being able to break itself away from the majority of its body. Also, the majority of the booster would be the fuel for the booster. More force is created as more fuel are pushed away from the tank and burnt faster, so the gas in the chamber would travel through faster away from the booster.
More the fuel are used, the mass of the entire booster would decrease. As Newton’s second law of motion, F=ma, if the force is constant and the mass decrease, there would be an increasing number in acceleration. For example, if you are riding a bicycle up a hill it would be more challenging if you are carrying heavier stuff along. Larger the mass, the greater the force it would require to travel further up the hill. To level things out, I often use momentum build from acceleration before riding up a hill.
So as the fuel for the booster in the first stage of the booster is used up, the booster would break away from the first stage. As the velocity attains, the booster would be able to start another fuel tank to travel farther away from the earth’s atmosphere. The speed would continue to increase and when the fuel tank in the second level finishes, the second tier tank would be broken away. Travel fast enough at the right distance the earth and the booster would able to be in orbit to the earth. The booster would to traveling away from the earth, as it falls towards the earth.
Reference
MIT Department of Aeronautics and Astronautics (1996) The Rocket. Retrieved from
