the laws of motion

a push or a pull on an object and is a vector (N)

to apply a force

a force that one object can apply on another object without touching

an attractive force that exists between all objects that have mass

the atom count of an object (kg)

every object is attracted to each other by a gravitational force

the force of gravity on an object (N)

When the mass of one or both objects increases, the gravitational force between them also increases.

Gravitational force decreases as the distance between them increases.

An object's weight is proportional to its mass

a force that resists the motion of two surfaces that are touching

prevents two surfaces from sliding past each other

opposes the motion of things that are already sliding past each other

Friction between a surface and a fluid, such as air or water

microscopic dips and bumps that slows sliding

A substance that reduces friction

The sum of all forces acting on an object

forces acting on an object that combine and form a net force of zero

forces acting on an object that combine and form a net force that is not zero

An object will keep doing what it's already doing unless an unbalanced force makes it do something else.

the constant velocity reached when air resistance equals the force of gravity on a falling object

The tendency of an object to resist a change in motion

Force and acceleration are directly related. Mass and acceleration are indirectly related.

a force that acts perpendicular to the direction of motion, toward the center of the curve

for every action force, there is always an equal and opposite reaction force

the forces two objects apply to each other

a measure of how hard it is to stop a moving object and is a vector

the total momentum of a group of objects stays the same unless outside forces act on the objects

Two objects bounce off each other.

two objects collide and stick together