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**Gravity Trivia Quiz Questions With Answers**

What is gravity?

A: Gravity is a natural phenomenon by which all things with mass or energy—including
planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another.

On Earth, gravity gives weight to physical objects, and the
Moon's gravity causes what?

A: The ocean tides.

Gravity has an infinite range, although its effects become increasingly weaker on what?

A: Farther objects.

Gravity is most accurately described by what theory?

A: The general theory of relativity.

Proposed by Albert Einstein in
1915, the general theory of relativity describes gravity not as a force, but as a what?

A: As consequence of the curvature of spacetime caused by the uneven distribution of mass.

The most extreme example of this curvature of spacetime is what?

A: A black hole, from which nothing—not even light—can escape once past the black hole's event horizon.

Gravity is the weakest of the four what?

A: Fundamental forces of physics.

A: Astronomical bodies.

Gravity causes the Earth and the other planets to orbit what?

A: The Sun, it also causes the Moon to orbit the Earth, and causes the formation of tides, the formation and evolution of the Solar System, stars and galaxies.

The earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during what period?

A: During the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner.

Modern work on gravitational theory began with the work of whom?

A: Galileo Galilei in the late 16th and early 17th centuries.

A: The same for all objects.

This was a major departure from Aristotle's belief that what?

A: Heavier objects have a higher gravitational acceleration.

Galileo postulated what as the reason that objects with less mass fall more slowly in an atmosphere?

A: Air resistance.

Galileo's work set the stage for the formulation of whose theory of gravity?

A: Newton's.

In 1687, English mathematician Sir Isaac Newton published what?

A: Principia, which hypothesizes the inverse-square law of universal gravitation.

Newton's theory enjoyed its greatest success when it was used to predict the existence of what?

A: Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets.

Calculations by both John Couch Adams and Urbain Le Verrier predicted the general position of the planet, and Le Verrier's calculations are what led whom to the discovery of Neptune?

A: Johann Gottfried Galle.

A: Mercury's.

By the end of the 19th century, it was known that its orbit showed slight perturbations that could not be accounted for under what?

A: Newton's theory, but all searches for another perturbing body (such as a planet orbiting the Sun even closer than Mercury) had been what fruitless.

The issue was resolved in 1915 by whose new theory of general relativity, which accounted for the small discrepancy in Mercury's orbit?

A: Albert Einstein's.

Although Newton's theory has been superseded by Einstein's general relativity, why are most modern non-relativistic gravitational calculations are still made using Newton's theory?

A: Because it is simpler to work with and it gives sufficiently accurate results for most applications involving sufficiently small masses, speeds and energies.

The equivalence principle, explored by a succession of researchers including Galileo, Loránd Eötvös, and Einstein, expresses the idea that what?

A: All objects fall in the same way, and that the effects of gravity are indistinguishable from certain aspects of acceleration and deceleration.

The simplest way to test the weak equivalence principle is to drop two objects of different masses or compositions in a vacuum and see whether they do what?

A: Hit the ground at the same time.

Such experiments demonstrate that all objects fall at the same rate when other forces (such as air resistance and electromagnetic effects) are what?

A: Negligible.

A: A torsion balance of a type invented by Eötvös.

In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of a what?

A: A force.

Einstein proposed that spacetime is curved by what?

A: Matter, and that free-falling objects are moving along locally straight paths in curved spacetime.

These straight paths are called what?

A: Geodesics.

Like Newton's first law of motion, Einstein's theory states that if a force is applied on an object, it would what?

A: Deviate from a geodesic.

Einstein discovered the field equations of what?

A: General relativity.

The Einstein field equations are a set of 10 what?

A: Simultaneous, non-linear, differential equations.

A: Spacetime.

A metric tensor describes a what?

A: A geometry of spacetime.

The prediction that time runs slower at lower potentials (gravitational time dilation) has been confirmed by what experiment?

A: The Pound–Rebka experiment (1959), the Hafele–Keating experiment, and the GPS.

The prediction of the deflection of light was first confirmed by whom?

A: Arthur Stanley Eddington from his observations during the Solar eclipse of 29 May 1919.

Eddington measured starlight deflections twice those predicted by Newtonian corpuscular theory, in accordance with what?

A: The predictions of general relativity.

However, his interpretation of the results was later what?

A: Disputed.

More recent tests using radio interferometric measurements of what, passing behind the Sun have more accurately and consistently confirmed the deflection of light to the degree predicted by general relativity?

A: Quasars.

A: Irwin I. Shapiro in 1964 in interplanetary spacecraft signals.

Gravitational radiation has been indirectly confirmed through studies of what?

A: Binary pulsars.

On 11 February 2016, the LIGO and Virgo collaborations announced the first observation of a what?

A: A gravitational wave.

General relativity predicts that light should lose its energy when traveling away from what?

A: Massive bodies through gravitational redshift.

When was this verified on earth and in the solar system?

A: Around 1960.

In the decades after the publication of the theory of general relativity, it was realized that general relativity is incompatible with what?

A: Quantum mechanics.

An initially-stationary object that is allowed to fall freely under gravity drops a distance that is proportional to what?

A: The square of the elapsed time.

A: Gravitational field, which can be conceptualized with Newtonian physics as exerting an attractive force on all objects.

Assuming a spherically symmetrical planet, the strength of this field at any given point above the surface is proportional to the planetary body's mass and inversely proportional to what?

A: The square of the distance from the center of the body.

If an object with comparable mass to that of the Earth were to fall towards it, then the corresponding acceleration of the Earth would be what?

A: Observable.

The rate of acceleration of falling objects near the Earth's surface varies very slightly depending on what?

A: Latitude, surface features such as mountains and ridges, and perhaps unusually high or low sub-surface densities.