Gravitation Essentials

Gravitation is the fundamental force of attraction between any two objects with mass. It governs the motion of planets, stars, and galaxies, and is described by Newton's Law of Universal Gravitation and Einstein's Theory of General Relativity.

Core Principles

Every particle attracts every other particle in the universe with a force proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
The gravitational force is always attractive and acts along the line joining the centers of the two masses.
Gravitational acceleration (g) is the acceleration experienced by an object due to gravity, and it varies with mass and distance from the celestial body.
Orbits are a balance between an object's inertia (tendency to move in a straight line) and the gravitational pull of a larger body.
Einstein's General Relativity describes gravity not as a force, but as a curvature of spacetime caused by mass and energy.
Black holes are regions of spacetime where gravity is so strong that nothing, not even light, can escape.

Formulas

$F = G \frac{m_1 m_2}{r^2}$
$g = G \frac{M}{r^2}$
$v = \sqrt{\frac{GM}{r}}$
$T^2 = \frac{4\pi^2}{GM} a^3$

Quiz

What is the primary force described by Newton's Law of Universal Gravitation?: Gravitational force
According to Newton's Law, if the distance between two masses doubles, how does the gravitational force change?: It becomes one-fourth
Einstein's theory describes gravity as a result of what?: The curvature of spacetime