Gravity

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Gravity Noun

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[grav-i-tee]

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Gravity

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A fundamental attractive force that acts between any two objects with mass, pulling them toward each other's center.

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Example: An apple falls from a tree branch, pulled downwards by the force of gravity, which is shown by the arrow.

Front

Mass Noun

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[mas]

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Mass

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The amount of matter in an object, which is a measure of its inertia and does not change with location.

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Example: This image shows a balance scale comparing a rock and a feather, visually demonstrating that the rock has more mass (more 'stuff') than the feather.

Front

Weight Noun

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[wayt]

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Weight

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The force exerted on an object's mass by gravity, which can vary depending on the gravitational field's strength.

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Example: A person stands on a scale, which measures weight. Weight is the force of gravity pulling the person's mass toward the center of the Earth.

Front

Law of Universal Gravitation Noun

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[law uv yoo-ni-vur-suhl grav-i-tay-shun]

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Law of Universal Gravitation

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The principle that every mass attracts every other mass with a force proportional to their masses and inversely to distance.

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Example: This image shows that two objects with mass, like the Earth and another celestial body, pull on each other with an equal gravitational force.

Front

Gravitational Constant (G) Noun

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[grav-i-tay-shun-uhl kon-stuhnt]

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Gravitational Constant (G)

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An empirical physical constant used to calculate the gravitational force between two bodies in Newton's law of gravitation.

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Example: This diagram shows that the Gravitational Constant (G) is the value used in the formula for calculating the force of gravity between two masses.

Front

Gravitational Acceleration Noun

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[grav-i-tay-shun-uhl ak-sel-uh-ray-shun]

Back

Gravitational Acceleration

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The acceleration of an object due to the force of gravity, which is approximately 9.8 m/s² near Earth's surface.

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Example: This diagram shows arrows pointing to Earth's center, representing the force of gravity, which constantly pulls objects, causing them to accelerate downwards.

Front

Projectile Noun

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[pro-jek-tahyl]

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Projectile

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Any object that is thrown or launched and continues to move under its own inertia and the force of gravity.

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Example: A projectile, like a cannonball, follows a curved path because while it moves forward, gravity constantly pulls it downward, away from its straight, gravity-free path.

Front

Inertia Noun

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[in-ur-shuh]

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Inertia

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The property of an object to resist any change in its state of motion, whether it is at rest or moving.

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Example: When the car stops suddenly, the passengers continue moving forward due to inertia, which is the resistance of an object to any change in its motion.

Front

Terminal Velocity Noun

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[tur-min-uhl vuh-los-i-tee]

Back

Terminal Velocity

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The constant speed that a freely falling object eventually reaches when air resistance equals the force of gravity.

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Example: As an object falls, air resistance (drag force) increases until it balances the force of gravity (weight), causing it to fall at a constant terminal velocity.

Front

Air Resistance Noun

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[air ri-zis-tuhns]

Back

Air Resistance

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A type of frictional force, also called drag, that acts upon objects as they move through the air.

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Example: This image shows that air resistance is a force that pushes up on falling objects, opposing gravity. It has a larger effect on a feather than a coin.