# Gravitation

## Newton’s Law of Gravitation

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

## Gravity between Spherical Bodies

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

## Acceleration due to Gravity on Earth

According to Newton's law of gravitation, the gravitational force on a body is proportional to its mass. According to Newton's second law of …

## Acceleration due to Gravity on Other Planets

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

## Apparent Weight and the Earth’s Rotation

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 towards …

## Variation in Acceleration due to Gravity near the Earth’s Surface

An object's apparent weight is its weight measured by a spring balance at its location. It is different from its true weight, the force with which the …

## Potential Energy due to Gravitation

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 it …

## Escape Velocity

The escape velocity of an object is defined as the minimum initial velocity that it requires to escape the surface of another object to which it is …

## Circular Orbits and Critical Velocity for Satellites

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 artificial …

## Energy of a Satellite in a Circular Orbit

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

## Kepler’s First Law of Planetary Motion

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

## Kepler’s Second Law of Planetary Motion

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

## Kepler’s Third Law of Planetary Motion

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

## Tidal Forces

The origin of Earth's ocean tides has been a subject of continuous investigation for over 2000 years. However, the work of Newton is considered to be …

## Schwarzschild Radius and Event Horizon

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 extremely …

## Detection of Black Holes

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

## Principle of Equivalence

According to Albert Einstein (1897-1955), free-falling and feeling weightless are intrinsically linked. If a person were in free-fall under gravity, for …

## Space-Time Curvature and the General Theory of Relativity

In 1905, Albert Einstein published his special theory of relativity. According to this theory, no matter in the universe can attain a speed greater than …

## 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 the …

## Gravitation Between Spherically Symmetric Masses

The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, …

## Reduced Mass Coordinates: Isolated Two-body Problem

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

## The Principle of Superposition and the Gravitational Field

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

## The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the …

## Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the …

## Thermocapillary Convection Space Experiment on the SJ-10 Recoverable Satellite

Thermocapillary convection is an important research subject in microgravity fluid physics. The experimental study on surface waves of thermocapillary …