Friction

Front

Friction Noun

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[frik-shun]

Back

Friction

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A force exerted by one surface on another that opposes the motion or tendency of motion between the two surfaces.

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Example: A car rolling onto a rough surface experiences friction, a force that opposes its forward motion, as shown by the opposing arrows.

Front

Kinetic Friction Noun

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[ki-net-ik frik-shun]

Back

Kinetic Friction

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The force exerted between two surfaces that are rubbing against each other because one or both of them are moving.

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Example: This diagram shows a force pushing a box, while kinetic friction is the opposing force that resists the box's movement across the surface.

Front

Static Friction Noun

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[stat-ik frik-shun]

Back

Static Friction

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The force exerted on one surface by another when there is no motion between them, preventing movement from starting.

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Example: When a force is applied to an object like a couch, static friction is the opposing force that prevents the object from moving.

Front

Normal Force Noun

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[nor-muhl fors]

Back

Normal Force

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The support force exerted by a stable object on another object in contact with it, acting perpendicular to the surface.

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Example: A book's weight pushes down on a table, and the table pushes back up with an equal and opposite normal force, keeping the book still.

Front

Coefficient of Kinetic Friction Noun

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[koh-uh-fish-uhnt uv ki-net-ik frik-shun]

Back

Coefficient of Kinetic Friction

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A dimensionless scalar value representing the ratio of the kinetic friction force to the normal force between two interacting surfaces.

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Example: The coefficient of kinetic friction (μk) is a value that, when multiplied by the normal force (N), calculates the force of kinetic friction (fk).

Front

Coefficient of Static Friction Noun

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[koh-uh-fish-uhnt uv stat-ik frik-shun]

Back

Coefficient of Static Friction

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A dimensionless scalar value representing the ratio of the maximum static friction force to the normal force between surfaces.

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Example: This diagram shows the forces on a block at rest. The coefficient of static friction (μs) is a value used in the formula to calculate the maximum static friction force (Fs) that prevents the block from moving.