Free Fall

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Gravity Noun

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[grav-i-tee]

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Gravity

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The universal force of attraction between any two objects that have mass, which causes them to move toward each other.

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Example: This diagram shows that Earth's gravity is a force that pulls everything towards its center, as represented by the yellow arrows pointing inward.

Front

Air Resistance Noun

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[air ri-zis-tuhns]

Back

Air Resistance

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The frictional force that air exerts against a moving object, opposing its motion as it travels through the air.

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Example: A parachute increases an object's surface area, creating a large upward force of air resistance that opposes gravity and slows the object's fall.

Front

Free Fall Noun

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[free fawl]

Back

Free Fall

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The motion of an object where gravity is the only significant force acting upon it, with negligible air resistance effects.

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Example: An apple falls from a branch, pulled downward only by the force of gravity, demonstrating the concept of free fall.

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 constant acceleration of an object due only to the force of gravity, approximately 9.8 m/s² downward near Earth.

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Example: This diagram shows a ball dropped from rest, which then speeds up as it falls, illustrating the constant downward acceleration due to gravity (g = 9.8 m/s²).

Front

Velocity Noun

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[vuh-los-i-tee]

Back

Velocity

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A vector quantity that specifies both the speed of an object and its precise direction of motion in space.

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Example: This image shows that velocity has both a speed (70 ft/sec) and a direction (a 40° angle), which determines the path of the thrown ball.

Front

Acceleration Noun

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[ak-sel-uh-rey-shuhn]

Back

Acceleration

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The rate at which an object's velocity changes over time; it is constant and directed downward during free fall.

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Example: An object in free fall increases its velocity by about 9.8 meters per second (m/s) for every second it falls, demonstrating constant acceleration.

Front

Displacement Noun

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[dis-pleys-muhnt]

Back

Displacement

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The overall change in an object's position, represented as a vector from the initial point to the final point.

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Example: A person moves from an initial position (x₀) to a final position (x_f), resulting in a displacement (Δx), the change in position.

Front

Trajectory Noun

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[truh-jek-tuh-ree]

Back

Trajectory

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The curved or straight path that a moving object follows through space as it travels under the action of forces.

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Example: This image shows the curved path, or trajectory, a soccer ball follows after being kicked. The path is shaped by the force of gravity pulling the ball down.