# Chapter 14
Gravitation

In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down…

Our everyday observation tells us that all objects close to the Earth naturally tend to fall to the ground. Early philosophers assumed that this…

Newton's law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the…

In classical mechanics, the two-body problem is one of the fundamental problems describing the motion of two interacting bodies under gravity or any…

The gravitational acceleration of an object near the Earth's surface is called the acceleration due to gravity. It can be measured by conducting…

Since all objects on the Earth's surface move through a circle every 24 hours, there must be a net centripetal force on each object, directed…

Since gravitational force is a conservative force, the amount of work done to move an object between two points in the gravitational field in which…

The principle of superposition applies to gravitational forces of objects that are sufficiently far apart. It states that the net gravitational force…

The Moon orbits around the Earth. In turn, the Earth (and other planets) orbit the Sun. The space directly above our atmosphere is filled with…

Thousands of artificial satellites orbit the Earth every day at various distances from the Earth. Satellites that orbit the Earth below an altitude…

In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system.…

No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of…

Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their…