Universal Gravitation

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Gravity Noun

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[grav-i-tee]

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Gravity

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The fundamental noncontact attractive interaction that exists between any two objects that possess mass.

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Example: This diagram shows that gravity is a mutual force of attraction between two objects with mass, like the Earth and another celestial body.

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Free Fall Noun

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[free fawl]

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Free Fall

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The motion of an object where gravity is the only significant force acting upon it, resulting in constant acceleration.

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Example: A satellite orbiting Earth is in a constant state of free fall, where Earth's gravity is the only force pulling it inward, causing it to continuously 'fall' around the planet.

Front

Weight Noun

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[wayt]

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Weight

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The gravitational force exerted on an object by a large celestial body, such as a planet or a star.

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Example: An object's mass (50 kg) stays the same, but its weight changes (110 lbs on Earth vs. 42 lbs on Mars) because weight is a measure of gravitational force.

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Mass Noun

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[mas]

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Mass

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A measure of the amount of matter in an object, which also determines its inertia or resistance to acceleration.

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Example: This image shows that an object's mass (1 kg) stays the same on both Earth and Mars, while its weight changes due to different gravity.

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Center of Mass Noun

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[sen-ter uv mas]

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Center of Mass

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The unique point in an object or system where the weighted relative position of its distributed mass sums to zero.

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Example: The center of mass (C) is the average position of all mass in a system. For two equal masses (m1 and m2), this balance point is exactly halfway between them.

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Gravitational Constant Noun

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[grav-i-tey-shuh-nl kon-stuhnt]

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Gravitational Constant

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The empirical physical constant that quantifies the magnitude of the gravitational force between two bodies in Newton's universal gravitation law.

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Example: This diagram shows two masses (m1, m2) attracting each other with a force (F) over a distance (r). The Gravitational Constant defines the strength of this universal attraction.

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Unit Vector Noun

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[yoo-nit vek-ter]

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Unit Vector

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A vector with a magnitude of exactly one, which is used to specify a particular direction in space.

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Example: This diagram shows the three standard unit vectors, î, ĵ, and k̂. Each has a length of one and points along the X, Y, or Z axis, defining directions in 3D space.

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Vector Noun

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[vek-ter]

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Vector

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A physical quantity that is defined by possessing both a magnitude and a specific direction in space.

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Example: This diagram shows an orbiting object. The arrows are vectors: the blue arrow shows the object's velocity (direction of motion) and the red arrow shows gravitational acceleration.

Front

Free-body Diagram Noun

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[free-bod-ee dahy-uh-gram]

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Free-body Diagram

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A graphical illustration used in physics to visualize all the external forces acting upon a single, isolated object.

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Example: This diagram shows all the forces acting on a book. The arrow 'W' represents weight (gravity pulling down), and other arrows show opposing forces.

Front

Vector Field Noun

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[vek-ter feeld]

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Vector Field

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A region in space where a vector quantity, such as force or velocity, can be assigned to every point.

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Example: This diagram shows a gravitational vector field. The arrows represent the direction and strength of the gravitational force at different points around two massive objects (M1, M2).