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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 …

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

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 towards …

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 …

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 …

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 …

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 …

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

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

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

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

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 …

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 …

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

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

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 …

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 …

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

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