acceleration

 The rate at which velocity is changing.

action force

 One pair of action forces that are described in Newton’s 3rd Law

force

 Any influence that tends to accelerate an object: a push or pull: measured in newtons.

interaction

 A mutual action between objects where each object exerts an equal and opposite force on the other.

law

A general hypothesis about the relationship of natural quantities that has been tested over and over again and has not been contradicted.

Newton's 3rd Law

 Whenever one body exerts a force on a second body: the second body exerts an equal and opposite force on the first.

mass

 A measure of an objects inertia: also a measure of the amount of matter in an object: Depends only on the amount of and kind of particles that compose of an object-not on its location.

motion

 An object that is moving

reaction force

 The force that is equal in strength and opposite in direction to the action force, which acts simultaneously on whateveris exerting the action force.

velocity

 Speed together with the direction of motion.

weight

The force on a body due to the gravitational attraction of another body.