Rockets overcome gravity through the principle of action and reaction, as described by Newton's third law of motion. This law states that for every action, there is an equal and opposite reaction. In the case of a rocket, it works by expelling high-speed exhaust gases in one direction, which generates a force in the opposite direction, propelling the rocket forward.
Here's a simplified explanation of how rockets overcome gravity:
Thrust: Rockets generate thrust by burning a combination of fuel and oxidizer in the combustion chamber of the rocket engine. The burning of fuel produces hot, high-pressure gases.
Exhaust gases: The hot gases are expelled through a nozzle at the rear of the rocket with high velocity. According to Newton's third law, the expulsion of these gases in one direction creates an equal and opposite reaction force that propels the rocket forward.
Conservation of momentum: The expulsion of the exhaust gases generates a forward momentum for the rocket due to the high-speed ejection. This momentum helps overcome the gravitational pull acting on the rocket.
Continuous propulsion: To maintain the upward motion and escape Earth's gravity, rockets need to provide continuous thrust. They carry large amounts of fuel and oxidizer on board, which are gradually burned during the ascent. As fuel is consumed, the rocket becomes lighter, increasing its acceleration and altitude.
Staging: Some rockets, such as those used in space exploration, employ a staging system. Multiple stages are stacked on top of each other, and each stage has its own engines. The lower stages are ignited first and provide the initial thrust, while the upper stages take over once their fuel is depleted. This staged approach allows the rocket to shed excess weight as it ascends.
It's important to note that while rockets can overcome Earth's gravity, they still experience the force of gravity throughout their journey. However, the initial thrust generated by the rocket is enough to overcome gravity's pull and propel the rocket into space.