Newton's First Law: an object with no force acting
on it moves with a constant velocity. More carefully stated, Newton's first
law is as follows: an object with no net force acting on it remains at rest
or moves with a constant velocity in a straight line.
Newton's Second Law: the acceleration of a body is directly
proportional to the net force on in and inversely proportional to its mass.
We can summarize the second law with the following equation:
a = F / m, or in a more common form:
F = ma. As you probably realized,
F = force, m = mass, and
a = acceleration.
Newton's Third Law: when one object exerts a force on
a second object, the second exerts a force on the first that is equal in
magnitude but opposite in direction. Restated, the law is as follows:
when one object exerts a force on a second object, the second object exerts
the force on the first that is the same in size but opposite in direction.
The magnitudes are always equal. The two forces are often called