Newton's First Law of Motion
Newton's first law of motion states that an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force.
Galileo's concept of the resistance to change in motion is called inertia.
Inertia is the tendency of an object to resist a change in motion.
Thus, the first law of motion is also called the law of inertia.
Newton's Second Law of Motion Newton's second law relates force, mass, and acceleration
Newton's Second Law of Motion
Force = Mass x Acceleration f = m x a
The greater the mass, the more force is needed to reach a certain acceleration