Using the Law of Universal Gravitation

Front

Elliptical Orbit Noun

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[uh-lip-ti-kuhl or-bit]

Back

Elliptical Orbit

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The oval-shaped path a planet or satellite takes around a central body, which is located at one of the two foci.

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Example: The Earth's elliptical orbit causes its distance from the Sun to vary, being closest at perihelion and farthest at aphelion.

Front

Orbital Period Noun

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[or-bi-tuhl peer-ee-uhd]

Back

Orbital Period

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The time required for a celestial body or an artificial satellite to complete one full revolution around another body.

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Example: This diagram shows the Moon's orbital path around Earth, caused by gravity. The orbital period is the time it takes to complete one full circle.

Front

Gravitational Force Noun

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[grav-i-tey-shuh-nl fors]

Back

Gravitational Force

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The mutually attractive force between any two objects with mass, which is fundamental to the structure of the universe.

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Example: This diagram shows that the gravitational force (F) between two objects (like Earth, m1, and the Moon, m2) depends on their masses and the distance (r) between them.

Front

Satellite Noun

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[sat-l-ahyt]

Back

Satellite

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An object, either natural or artificial, that revolves in a curved path around a larger celestial body due to gravity.

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Example: A satellite stays in orbit because gravity provides a constant inward pull (red arrow), while its forward velocity (blue arrow) keeps it from falling.

Front

Orbit Noun

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[or-bit]

Back

Orbit

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The curved, often elliptical, path that an object takes as it revolves around another object due to gravitational attraction.

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Example: This diagram shows the Earth following a curved path, its orbit, around the Sun. This path is caused by the Sun's gravitational pull on the Earth.

Front

Centripetal Acceleration Noun

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[sen-trip-i-tl ak-sel-uh-rey-shuhn]

Back

Centripetal Acceleration

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The acceleration of an object moving in a circular path, directed toward the center of the circle, maintaining its orbit.

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Example: An object moving in a circular path, like a planet in orbit, constantly accelerates towards the center. This is called centripetal acceleration.

Front

Geosynchronous Orbit Noun

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[jee-oh-sing-kruh-nuhs or-bit]

Back

Geosynchronous Orbit

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An orbit where a satellite's orbital period matches Earth's rotation, causing it to appear stationary above a single point.

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Example: This diagram shows a satellite in an inclined orbit around the rotating Earth, where the satellite's orbital period matches Earth's rotation, a state maintained by gravity.

Front

Free-fall Acceleration Noun

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[free-fawl ak-sel-uh-rey-shuhn]

Back

Free-fall Acceleration

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The acceleration of an object due solely to the influence of gravity, without any other forces like air resistance acting.

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Example: Earth's mass creates a gravitational field, shown by arrows, that pulls objects toward its center, causing them to accelerate in free-fall.

Front

Apparent Weightlessness Noun

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[uh-par-uhnt weyt-lis-nis]

Back

Apparent Weightlessness

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The condition experienced by objects in free-fall, where no contact forces are exerted, creating the sensation of zero weight.

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Example: A satellite is in constant freefall toward Earth due to gravity (F). Its high sideways velocity (v) makes it continuously miss, causing apparent weightlessness.

Front

Gravitational Field Noun

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[grav-i-tey-shuh-nl feeld]

Back

Gravitational Field

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A region of space surrounding a massive object where another object would experience a force due to gravity.

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Example: An object with mass, like Earth, creates a gravitational field around it, causing a force (F) that pulls other objects toward it.