Balanced and Unbalanced Forces

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Force Noun

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[fors]

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Force

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A push or pull on an object that can change its motion, measured in Newtons and possessing a direction.

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Example: A kicked soccer ball experiences multiple forces. The combination of the applied force, air resistance, and gravity results in an unbalanced force, changing its motion.

Front

Newton (N) Noun

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[noo-tn]

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Newton (N)

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The standard unit of measurement for force in the International System of Units, representing the force needed to accelerate one kilogram at one meter per second squared.

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Example: This image shows Newton's Second Law, F=ma, explaining that a force (measured in Newtons, N) is the product of an object's mass and its acceleration.

Front

Vector Quantity Noun

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[vek-ter kwon-ti-tee]

Back

Vector Quantity

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A physical quantity that is fully described by having both a magnitude, or size, and a specific direction.

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Example: This image shows forces represented as arrows, which are vectors. The arrow's length indicates the force's magnitude (strength), and its direction shows where it is being applied.

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Gravity Noun

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[grav-i-tee]

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Gravity

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A fundamental, non-contact force of attraction that acts between any two objects that possess mass or energy.

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Example: The force of gravity is an unbalanced force that pulls the apple down from the tree branch, causing it to fall towards the ground.

Front

Friction Noun

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[frik-shun]

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Friction

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A contact force that opposes the relative motion or tendency of such motion between two surfaces in contact.

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Example: This diagram shows friction as a force that opposes the motion of a box being pushed, caused by the microscopic roughness between the two surfaces.

Front

Air Resistance Noun

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[air ri-zis-tuhns]

Back

Air Resistance

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A type of friction, also known as drag, that opposes the motion of an object as it moves through air.

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Example: This image shows air resistance as a force pushing against moving objects, such as an airplane, and opposing the downward pull of gravity on falling feathers and leaves.

Front

Net Force Noun

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[net fors]

Back

Net Force

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The overall force acting on an object, calculated as the vector sum of all individual forces applied to it.

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Example: This diagram shows how to find the net force on a cart. When forces push in the same direction, they add together. When they push in opposite directions, they subtract.

Front

Balanced Forces Noun

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[bal-uhnst for-sez]

Back

Balanced Forces

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Two or more forces that are equal in size and opposite in direction, resulting in a net force of zero.

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Example: This image shows two people pulling a rope with equal and opposite force, so neither person moves, demonstrating balanced forces.

Front

Unbalanced Forces Noun

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[un-bal-uhnst for-sez]

Back

Unbalanced Forces

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Forces that are unequal in size or not opposite in direction, resulting in a non-zero net force and acceleration.

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Example: The horizontal forces pushing the box are unequal (100 N vs. 50 N), creating a net force that will cause the box to move.

Front

Inertia Noun

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[in-ur-shuh]

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Inertia

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

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Example: A crash test dummy continues to move forward due to inertia, even after the car it is in has suddenly stopped by an unbalanced force.