Integrated SequencePhysics Chemistry Organic Biology

WikiPremed Resources

Module 3 in the Syllabus

Gravitation Cards
Chapter from the Wisebridge Learning System for Physics

Gravitation Images
Image gallery for study with links to larger teaching JPEGs for classroom presentation

Question Drill for Gravitation
Conceptual Vocabulary Self-Test

Basic Terms Crossword Puzzle

Basic Puzzle Solution

Overview of Gravitation
Gravitation describes the mutual attraction of all bodies that occurs due to their mass. The basis of the study of gravitation in classical physics is Newton's Law of Universal Gravitation (Einstein's General Theory of Relativity has supplanted the Law of Universal Gravitation in advanced discussions). The Law of Universal Gravitation allows us to predict the forces between two particles a given distance apart. We can also predict the gravitational force exerted per unit mass at a given point in space, in other words, the gravitational field that a mass creates in its vicinity describing its capacity to exert force on other masses.

Gravitation on the MCAT
Gravity problems appear fairly regularly on the MCAT. On the MCAT you will often see permutations of such classic gravity problems as satellite orbit or escape velocity. Additionally, as an 'inverse square law force', gravitation has many important similarities in problem solving to the electrostatic force. Though there are a host of important differences, gravitation is important for laying some important groundwork for understanding and modelling force and energy relationships in electrostatics.

Conceptual Vocabulary
GravitationGravitation is a natural phenomenon by which all objects with mass attract each other.
TideTides are the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans.
Center of massThe center of mass of a system of particles is a specific point at which, for many purposes, the system's mass behaves as if it were concentrated.
Gravitational fieldThe gravitational field around a single particle in classical mechanics is a vector field pointing directly towards the particle giving the magnitude of the force per unit mass for the array of points in space.
OrbitA orbit is the path that an object makes around another object while under the influence of a centripetal force such as gravity.
Escape velocityEscape velocity is the speed where the kinetic energy of an object is equal in magnitude to its potential energy in a gravitational field.
General relativityGeneral relativity is the geometrical theory of gravitation published by Albert Einstein in 1915-16 unifying special relativity and Newton's law of universal gravitation.
Standard gravityStandard gravity is the nominal acceleration due to gravity at the Earth's surface at sea level.
Gravitational binding energyThe gravitational binding energy of an object consisting of loose material, held together by gravity alone, is the amount of energy required to pull all of the material apart, to infinity.
Inverse-square lawAn inverse-square law is any physical law stating that some physical quantity or strength decreases proportional to the square of the distance from the source of that physical quantity.
Cavendish experimentThe Cavendish experiment, performed in 1797 - 1798, was the first experiment to measure the force of gravity between laboratory masses.
Orbital periodThe orbital period is the time it takes a planet (or another object) to make one full orbit.
Geosynchronous satelliteA geosynchronous satellite is a satellite whose orbital track on the Earth repeats regularly over points on the Earth over time.
Geosynchronous orbitA geosynchronous orbit is an orbit around the Earth with an orbital period matching the Earth's sidereal rotation period.
Geostationary orbitA geostationary orbit is a geosynchronous orbit directly above the Earth's equator, with orbital eccentricity of zero. From the ground, such an object appears motionless in the sky.
Circular orbitA circular orbit is an elliptic orbit with the eccentricity equal to zero.
EllipseAn ellipse is the locus of points on a plane where the sum of the distances from any point on the curve to two fixed points is constant.
Astronomical unitThe astronomical unit is a unit of length nearly equal to the semi-major axis of Earth's orbit around the Sun.
PerigeePerigee is the point at which an object in orbit around the Earth makes its closest approach to the Earth.
Kepler's laws of planetary motionJohannes Kepler (1571 - 1630) was a German mathematician whose primary contributions to astronomy and astrophysics were his three laws of planetary motion.
PerturbationPerturbation is a term used in astronomy to describe alterations to an object's orbit caused by gravitational interactions with other bodies.
ApsisAn apsis is the point of greatest or least distance of the elliptical orbit of an astronomical object from its center of attraction.
HeliocentrismHeliocentrism is the theory that the sun is at the centre of the Universe and/or the Solar System.
Low Earth orbitA low Earth orbit is generally defined as an orbit within the locus extending from the Earth's surface up to an altitude of 2,000 km.
Specific orbital energyThe specific orbital energy of an orbiting body traveling through space is the sum of its potential energy and kinetic energy per unit mass.
Standard gravitational parameterThe standard gravitational parameter of a celestial body is the product of the gravitational constant and the mass.

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