Welcome! Today we'll explore how rockets fly. Rockets work based on Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When a rocket burns fuel, it expels hot gas downward at high speed. This downward action creates an equal and opposite upward reaction, pushing the rocket into the sky.
The rocket engine works through a carefully controlled combustion process. First, fuel and oxidizer are injected into the combustion chamber where they mix together. When ignited, this mixture burns at extremely high temperatures, creating hot gas that expands rapidly. This expansion creates enormous pressure inside the chamber, pushing against all walls equally.
The key to rocket flight is creating thrust. The nozzle shapes and accelerates the hot gas, directing it downward at extremely high velocity. According to Newton's third law, as the rocket pushes gas downward, the gas pushes back on the rocket with equal force upward. This upward force is called thrust. The amount of thrust depends on both the mass flow rate of the gas and its exit velocity.
Several forces act on a rocket during flight. Thrust pushes the rocket upward, generated by expelling gas downward. Weight pulls the rocket down due to gravity. Drag opposes the rocket's motion through the atmosphere. For a rocket to lift off and accelerate upward, the thrust force must be greater than the combined weight and drag forces. This creates a net upward force that accelerates the rocket skyward.
Here's the complete rocket launch sequence in action. The rocket ignites and lifts off from the ground, accelerating upward as thrust overcomes weight and drag. It passes through the atmosphere, gradually gaining speed and altitude. Eventually, it reaches space where there's no air resistance. This entire process perfectly demonstrates Newton's Third Law: the rocket pushes gas downward, and the gas pushes the rocket upward, enabling human space exploration.