Newton's First Law
Definition of Newton's first law
Newton's law was that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless an unbalanced force acts upon it.
Definition of Inertia
Inertia is the resistance of any physical object to change in its state of motion including changes in its speed and direction or state of rest. It is the tendency of objects to keep moving in a straight line.