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Speed

Distance travelled per unit time.

Instantaneous

The speed of an object at one instant of time.

Average Speed

The overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time.

Velocity

Speed in a given direction.

Acceleration

A rate of change of velocity.

Force

A push or a pull.

Balanced Force

Equal forces acting on an object in opposite directions.

Unbalanced Force

Forces that produce a nonzero net force, which changes an object's motion.

Inertia

The tendency of a body to maintain is state of rest or uniform motion unless acted upon by an external force.

Friction

A force that opposes motion between two surfaces that are in contact.

Mass

A measure of the amount of matter in an object.

Weight

A measure of the force of gravity on an object.

Air resistance

The fluid friction experienced by objects falling through the air.

Momentum

Mass x Velocity.

Newton (unit)

Measurement of force, kg x m/s2.

Newton's First Law Of Motion

"An object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force." Another name is Law of Inertia.

Newton's Second Law Of Motion

The acceleration of an object depends on the mass of the object and the amount of force applied.

Newton's Third Law Of Motion

For every action there is an equal and opposite reaction.