- mass (m) - A measure of a body's resistance to acceleration. The SI unit of mass is the kilogram (kg), which gives the ratio of the mass of an object to a standard mass.
- force (F) - A vector quantity that produces an acceleration of a body in the direction of its application. The SI unit of force is the newton (N). 1 N = 1 kg m s^{-2}
net force - The vector sum of all the forces acting on a body or system.
Newtons first law - Any object continues at rest, or at constant velocity, unless an external force acts on it.
Newtons second law - An external force gives the object an acceleration which is proportional to the force.
F = m
a
Newtons third law - For every action there is an equal and opposite reaction.
friction force (
f)
normal force (N) - The perpendicular component of the contact force between two objects in physical contact with each other.
action-reaction pair - Newtons third law states that for every reaction, there is an equal and opposite reaction. These two forces form an 'action-reaction' pair that are equal in magnitude and opposite in direction. An alternative name is Newton's third-law pair.
tension force (
T) - A force that tends to stretch intermolecular bonds.
drag - The resistance an object encounters moving through a fluid/gasses.