Circular and Rotational Motion

Front

Axis of Rotation Noun

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[ak-sis uv roh-tey-shuhn]

Back

Axis of Rotation

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The imaginary straight line around which a rigid body rotates, with all points on the body moving in circles.

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Example: This diagram shows the Earth spinning on its axis of rotation, an imaginary line through its center, which causes the cycle of day and night.

Front

Angular Displacement Noun

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[ang-gyuh-ler dis-pleys-muhnt]

Back

Angular Displacement

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The angle through which a point, line, or body is rotated in a specific direction around a particular axis.

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Example: This diagram shows that angular displacement (θ) is the angle an object rotates around a central point, moving along an arc (s) of a circle.

Front

Angular Velocity Noun

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[ang-gyuh-ler vuh-los-i-tee]

Back

Angular Velocity

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The rate of change of angular displacement, indicating how fast an object rotates or revolves about an axis over time.

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Example: This diagram shows that angular velocity (w) is how fast an object rotates, measured by the angle (θ) it sweeps through in a certain amount of time (t).

Front

Angular Acceleration Noun

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[ang-gyuh-ler ak-sel-uh-rey-shuhn]

Back

Angular Acceleration

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The time rate of change of angular velocity, representing how quickly an object's rotation speed or direction is changing.

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Example: Applying a tangential force to a bike tire causes it to spin faster, demonstrating angular acceleration, which is the rate of change of its rotational speed.

Front

Tangential Speed Noun

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[tan-jen-shuhl speed]

Back

Tangential Speed

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The linear speed of an object moving along a circular path, directed tangent to the circle at any given point.

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Example: An object moving in a circle has a tangential speed, shown by the blue arrows, which is always directed straight ahead, tangent to the circular path.

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 towards the center of the circle due to a change in direction.

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Example: An object moving in a circle has a velocity tangent to the path, but an inward force continuously pulls it, causing it to accelerate towards the center.

Front

Centripetal Force Noun

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[sen-trip-i-tl fawrs]

Back

Centripetal Force

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The net force that acts on an object to keep it moving in a circular path, always directed towards the center.

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Example: This diagram shows an object moving in a circle, with an arrow pointing inward labeled 'Centripetal force,' illustrating the force that pulls it toward the center.

Front

Gravitational Field Strength Noun

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[grav-i-tey-shuhn-l feeld strength]

Back

Gravitational Field Strength

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The gravitational force exerted per unit mass on an object, which is equivalent to the free-fall acceleration at that location.

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Example: The arrows show Earth's gravitational field, an invisible area of force that pulls all objects toward the planet's center.

Front

Apparent Weightlessness Noun

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

Back

Apparent Weightlessness

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The condition in which an object seems to be weightless because it is in a state of continuous free fall.

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Example: A satellite in orbit is constantly falling toward Earth due to gravity (F), but its high forward speed (V) causes it to continuously miss, creating apparent weightlessness.

Front

Torque Noun

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[tawrk]

Back

Torque

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A twisting force that tends to cause rotation, measuring the ability of a force to rotate an object around an axis.

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Example: Applying a force (F) to the handle of a wrench creates a twisting force, or torque, which causes the nut to rotate around a pivot point.