Motion

Front

Net Force Noun

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[net fors]

Back

Net Force

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The overall force acting on an object after all individual forces are combined, determining its change in motion.

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Example: Two figures pull a cart in opposite directions. The net force is the combination of these forces, determining the cart's direction of motion.

Front

Friction Noun

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[frik-shun]

Back

Friction

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A force that opposes the motion of objects that touch as they move past each other.

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Example: This image shows that as a car moves forward (motion), friction is the force from the surface that pushes back in the opposite direction.

Front

Static Friction Noun

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[stat-ik frik-shun]

Back

Static Friction

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The friction force that acts on objects that are not moving, preventing them from starting to move.

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Example: An applied force pushing a couch is opposed by an equal static frictional force, so the couch does not move.

Front

Sliding Friction Noun

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[sly-ding frik-shun]

Back

Sliding Friction

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A force that opposes the direction of motion of an object as it slides over a surface.

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Example: This diagram shows a force pushing a box, while sliding friction is the opposing force. A magnified view reveals that friction is caused by microscopic bumps on the surfaces rubbing together.

Front

Rolling Friction Noun

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[rohl-ing frik-shun]

Back

Rolling Friction

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The friction force that acts on rolling objects, opposing their motion as they roll over a surface.

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Example: When a wheel is pushed, it rolls forward, but rolling friction is a force that acts in the opposite direction to resist this motion.

Front

Fluid Friction Noun

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[floo-id frik-shun]

Back

Fluid Friction

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A force that opposes the motion of an object as it moves through a fluid like air or water.

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Example: An object moving through a fluid (like water or air) experiences a resistive force called fluid friction, which acts in the opposite direction of its motion.

Front

Air Resistance Noun

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[air ri-zis-tuhns]

Back

Air Resistance

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A specific type of fluid friction that acts on an object moving through the air, opposing its motion.

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Example: The large parachute creates significant upward air resistance, which opposes the downward pull of gravity, slowing the person's fall to a low speed.

Front

Terminal Velocity Noun

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[tur-muh-nl vuh-los-i-tee]

Back

Terminal Velocity

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The constant velocity of a falling object when the upward force of air resistance equals the downward force of gravity.

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Example: A falling object reaches terminal velocity when the upward force of air resistance (drag) perfectly balances the downward force of gravity, causing constant speed.

Front

Projectile Motion Noun

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[pruh-jek-tahyl moh-shun]

Back

Projectile Motion

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The curved path an object follows when thrown near the Earth's surface, combining horizontal and vertical motion.

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Example: This diagram shows the curved, parabolic path an object follows when launched at an angle, influenced only by gravity.

Front

Inertia Noun

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[in-ur-shuh]

Back

Inertia

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The tendency of an object to resist any change in its state of motion, whether at rest or moving.

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Example: The image shows inertia: a ball at rest needs a force (kick) to move, and a ball in motion needs a force (net) to stop.