Weight and Drag Force

Front

Weight Noun

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[wayt]

Back

Weight

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The gravitational force experienced by an object, calculated as the product of its mass and the local gravitational field strength.

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Example: This image shows that an object's mass (50 kg) stays the same, but its weight changes (110 lbs on Earth vs. 42 lbs on Mars) depending on the planet's gravity.

Front

Gravitational Force Noun

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[grav-i-tey-shuh-nl fors]

Back

Gravitational Force

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A fundamental, non-contact attractive force that exists between any two objects with mass, pulling them toward each other.

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Example: This diagram shows that Earth's gravitational force is an attractive force that pulls everything towards its center, which is what gives objects weight.

Front

Gravitational Field (g) Noun

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[grav-i-tey-shuh-nl feeld]

Back

Gravitational Field (g)

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A vector quantity describing the gravitational force per unit mass at a specific location, such as near a planet's surface.

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Example: This diagram shows that a mass (M) creates a gravitational field around it, with the force pulling other objects radially inward, toward the center.

Front

Newton Noun

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[noo-tn]

Back

Newton

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The standard International System (SI) unit of force, required to accelerate one kilogram of mass at one meter per second squared.

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Example: This diagram shows Newton's second law, F=ma, which defines the unit of force (Newton) as the product of an object's mass and its acceleration.

Front

Apparent Weight Noun

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[uh-pair-uhnt wayt]

Back

Apparent Weight

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The support force exerted on an object, which can differ from its actual weight if the object is accelerating vertically.

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Example: For an object at rest on a surface, the upward support force, called apparent weight, is equal and opposite to the downward force of gravity (weight).

Front

Weightlessness Noun

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[wayt-lis-nis]

Back

Weightlessness

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The condition in which an object's apparent weight is zero because no contact forces are acting to support it.

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Example: This diagram shows a satellite in orbit. It is constantly falling towards Earth (Force F) but has enough sideways speed (velocity v) to miss, causing apparent weightlessness.

Front

Free Fall Noun

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[free fawl]

Back

Free Fall

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The motion of an object where gravity is the only significant force acting on it, causing a constant downward acceleration.

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Example: An object in free fall accelerates downwards due to gravity (g), starting from rest (initial velocity u=0) from a certain height (H).

Front

Drag Force Noun

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[drag fors]

Back

Drag Force

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A resistive force exerted by a fluid, such as air or water, that opposes an object's motion through it.

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Example: As a parachute falls, its weight pulls it down while drag force (air resistance) pushes up, opposing the motion and slowing the descent.

Front

Terminal Velocity Noun

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

Back

Terminal Velocity

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The constant speed a falling object reaches when the drag force equals the force of gravity, resulting in zero acceleration.

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Example: When a falling object reaches terminal velocity, the upward force of air resistance (drag) becomes equal to the downward force of its weight.

Front

Mass Noun

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[mas]

Back

Mass

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An intrinsic property of matter that measures its inertia and the amount of substance in an object, distinct from weight.

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Example: This image uses a balance scale to show that the rock has more mass (more 'stuff') than the feather, causing the scale to tip.