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100

Strength or energy as an attribute of physical action or movement 

Force 

100

The force that occurs when a wheel, ball, or cylinder rolls freely over a surface.

Rolling Friction 

100

The friction between layers of a viscous fluid that are moving relative to each other.

Fluid Friction 

100

A body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.

Weight

100

A fundamental force of nature that underlies some forms of radioactivity, governs the decay of unstable subatomic particles such as mesons, and initiates the nuclear fusion reaction that fuels the Sun.

Weak Nuclear Force

200
The SI unit of force. It is equal to the force that would give a mass of one kilogram an acceleration of one meter per second per second, and is equivalent to 100,000 dynes.


Newton

200

When a particle is thrown obliquely near the earth's surface, it moves along a curved path under constant acceleration directed towards the center of the earth.

Projectile Motion

200

The vector sum of forces acting on a particle or object.

Net Force

200

The quantity of motion of a moving body, measured as a product of its mass and velocity.

Momentum

200

The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface.

Gravitational Force

300

The resistance that one surface or object encounters when moving over another.

Friction

300
The forces that are in opposition to the relative motion of an object as it passes through the air.



Air Resistance 

300

The law that states that within some problem domain, the amount of momentum remains constant; momentum is neither created nor destroyed, but only changed through the action of forces as described by Newton's laws of motion.

Law of Conservation of Momentum

300
A force that acts on a body moving in a circular path and is directed toward the center around which the body is moving.


Centripetal Force

400

The force of friction on an object that is not moving

Static Friction

400

The force that attracts a body toward the center of the earth, or toward any other physical body having mass.

Gravity

400

A property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

Inertia

400

A type of physical interaction that occurs between electrically charged particles.

Electromagnetic Force

500

The force that opposes the movement between two contact surfaces that slide against each other

Sliding Friction

500
The constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration.


Terminal Velocity

500

A dimensionless quantity representing the amount of matter in a particle or object.

Mass

500

The electrical force pushing protons apart and the strong force acting on both protons and neutrons inside of a nucleus.

Strong Nuclear Force

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