ScienceVerseLearning path: Spaceflight
The concepts to learn before Spaceflight, in order. Each step links to its page and, where one exists, its quiz.
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Your path
- ForcesDirect prerequisite
A push or pull interaction between two objects, capable of changing an object's velocity. Newton's three laws of motion describe how forces and motion relate: a body keeps its state of motion unless acted on by a net force (first law), net force equals mass times acceleration, F = ma (second law), and forces between two bodies are equal and opposite (third law).
- GravityDirect prerequisite
The attractive force between any two masses. Newton's law of universal gravitation describes it as proportional to the product of the two masses and inversely proportional to the square of the distance between them. Near Earth's surface this produces a roughly constant downward acceleration of about 9.8 m/s^2 on falling objects.
- MomentumDirect prerequisite
The product of an object's mass and velocity, a vector quantity describing the 'quantity of motion' it carries. In a closed system with no external forces, total momentum before and after an interaction such as a collision is conserved, even when kinetic energy is not (as in an inelastic collision).
- Solar SystemDirect prerequisite
The Sun and everything gravitationally bound to it: eight planets, their moons, dwarf planets such as Pluto, and countless smaller bodies including asteroids and comets. The Sun's gravity holds the whole system together and keeps the planets in elliptical orbits described by Kepler's laws of planetary motion.
- SpaceflightYour goal
Spaceflight is travel beyond Earth's atmosphere, made possible by rockets that push themselves forward by throwing exhaust backwards. Reaching orbit means going sideways fast enough — about 8 km/s — to keep falling around Earth without hitting it, and the rocket equation shows why most of a rocket's launch weight must be propellant. Since Sputnik in 1957, spaceflight has carried satellites, telescopes and people into orbit and astronauts to the Moon.