Newton's First Law
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Inertia
The tendency of an object to resist a change in motion
free body diagram
a physical model that represents the forces acting on a system
net force
The sum of all forces acting on an object
balanced force
two forces acting in opposite directions on an object, and equal in size
unbalanced forces
Forces that produce a nonzero net force, which changes an object's motion
Newton's Second Law
Force equals mass times acceleration
normal force
the perpendicular contact force exerted by a surface on another object
Weight
A measure of the force of gravity on an object
friction
A force that opposes motion between two surfaces that are in contact
Tension Force
The force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends
applied force
a force that is put on an object by another object
direct proportion
a relationship in which the ratio of two variables is constant
inverse proportion
a relation between two quantities such that one increases in proportion as the other decreases.
Newton's Third Law
For every action there is an equal and opposite reaction
static friction
Friction that acts on objects that are not moving
kinetic friction
Friction between moving surfaces
air resistance
Fluid friction acting on an object moving through the air
work
Force exerted on an object that causes it to move
power
the rate at which work is done