The state in which one object's distance from another is changing.
Motion
The overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time.
Average speed.
A push or pull exerted on an object.
Force
Fricton that acts between objects that are not moving.
Static Friction.
A measure of the force of gravity acting on an object.
Weight.
A place or object used for comparison to determine if an object is in motion.
Reference Point
The speed of an object at one instant of time.
Instantaneous Speed.
A unit of measure that equals the force required to accelerate 1 kilogram of mass at 1 meter per second.
Newton.
Friction that occurs as an object moves through a fluid.
Fluid Friction.
The tendency of an object to resist a change in motion.
Inertia.
A system of measurement based on multiples of ten and on established measures of mass, length, and time.
International System of Units
Speed in a given direction.
Velocity.
The overall force on an object when all the individual forces acting on it are added together.
Net Force.
Friction that occurs when an object rolls over a surface.
Rolling Friction.
The length of the path between two points.
Distance.
The steepness of a graph line; the ratio of the vertical change to the horizontal change.
Slope.
The force that two surfaces exert on each other when they rub against each other.
Friction.
The attractive force between objects; the force that moves objects downhill.
Gravity.
The distance an object travels per unit of time.
Speed.
The rate at which velocity changes.
Acceleration.
Friction that occurs when one solid surface slides over another.
Sliding Friction.
The amount of matter in a object.
Mass.