Circular Motion

Front

Uniform Circular Motion Noun

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[yoo-nuh-form sur-kyuh-ler moh-shuhn]

Back

Uniform Circular Motion

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The movement of an object at a constant speed around a circle with a fixed radius.

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Example: This diagram shows an object moving in a circle. The blue arrow is its velocity (direction of motion), and the red arrow is the inward acceleration that keeps it on the circular path.

Front

Velocity Noun

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[vuh-los-i-tee]

Back

Velocity

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A vector quantity representing the rate of change of an object's position, which is always tangent to the circular path.

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Example: For an object moving in a circle, its velocity at any instant is a vector (shown by the arrow 'v') that points tangent to the circular path.

Front

Position Vector Noun

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[puh-zish-uhn vek-ter]

Back

Position Vector

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A displacement vector with its tail at the origin, used to describe an object's position relative to a central point.

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Example: A position vector is an arrow (like vector 'r') that points from a starting point (origin 'O') to the location of an object (point 'P').

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 center-seeking acceleration of an object in uniform circular motion, which always points toward the center of the circle.

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Example: An object in circular motion has a velocity pointing sideways, but an inward force constantly pulls it, causing it to accelerate towards the center.

Front

Period Noun

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[peer-ee-uhd]

Back

Period

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The time required for an object moving in a circular path to make one complete revolution or cycle.

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Example: This diagram shows a pendulum, where the 'Period' is the time it takes to complete one full swing back and forth, which is 2.0 seconds in this example.

Front

Revolution Noun

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[rev-uh-loo-shuhn]

Back

Revolution

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One complete trip or cycle of an object moving in a circular path around a central point or axis.

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Example: This diagram shows the Earth's revolution, its year-long elliptical orbit around the Sun, which is a central concept in circular motion.

Front

Centripetal Force Noun

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[sen-trip-i-tl fohrs]

Back

Centripetal Force

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The net force directed toward the center of a circle that causes an object to follow a circular path.

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Example: An object moving in a circle has a velocity tangent to the path and is pulled inward by a centripetal force, which keeps it from flying off.

Front

Tension Noun

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[ten-shuhn]

Back

Tension

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A pulling force transmitted axially through a string, cable, or chain, which can act as a centripetal force.

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Example: A block hanging from a string demonstrates tension, a pulling force transmitted through the string that counteracts the weight of the block.

Front

Tangential Adjective

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[tan-jen-shuhl]

Back

Tangential

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In the direction of a tangent line to a curve, describing the direction of velocity in circular motion.

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Example: This diagram shows that if an object spinning in a circle is released at point A, it will fly off in a straight line (path 2) tangential to the circle.

Front

Fictitious Force Noun

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[fik-tish-uhs fohrs]

Back

Fictitious Force

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A nonexistent force that appears to act on a mass whose frame of reference is accelerating relative to an inertial frame.

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Example: From the ground, a rolled ball travels straight. From the spinning merry-go-round, the ball's path seems to curve due to a 'fictitious force'.