How a rocket reaches orbit · OakCrest Academy

🚀 How a rocket reaches orbit

A rocket throws gas backward, and by Newton's third law the gas pushes the rocket forward with an equal force.
The engine burns liquid methane with liquid oxygen (CH₄ + 2O₂ → CO₂ + 2H₂O), and its narrow throat and widening bell speed the hot gas to over 3 km/s.
The rocket leaves the ground only when thrust is greater than weight: 22 engines × 230 t just beat a 5,000 t rocket.
The rocket equation, Δv = vₑ × ln(m₀ ÷ m_f), shows why a rocket is mostly propellant and why dropping an empty stage adds speed.
To stay in orbit a spacecraft must fly sideways at about 7.8 km/s, so it keeps falling around the Earth instead of into it.
A reusable booster flips, burns back toward home, steers with grid fins and slows with a landing burn before the tower catches it.

New words

thrust: the forward push a rocket gets from throwing its exhaust backward
specific impulse: a measure of engine efficiency: exhaust speed divided by 9.81 m/s², given in seconds
chamber pressure: how hard the burning gas presses inside the engine, about 300 times air pressure in this engine
mass ratio: the rocket's full mass divided by its empty mass, m₀ ÷ m_f
delta-v (Δv): the total change in speed a rocket can make with the propellant it carries
gravity turn: tipping the rocket over gently after liftoff so gravity bends its path toward flying level

🏠 Try it for real

With a grown-up, thread a 3 m string through a drinking straw, tie it tight between two chairs, tape a blown-up balloon under the straw and let go. Measure how far it travels with one, two and three breaths of air.

💭 Talk about it

Why do rockets usually come in stages, and what would have to change for a single stage to reach orbit?

Now explain it back: point at each part and say what it does.