# Newtons first law of motion

See the below image for the Newtons first law of motion diagram. Newton’s first law is often referred to as the principle of inertia . Newton’s first (and second) laws are valid only in an inertial reference frame. The second law states that the rate of change of momentum of a body over time is directly proportional to the force applied, and occurs in the same direction as the applied force.

Everyday Applications of Newton’s First Law. The force of the road on the locked wheels provides the unbalanced force to change the car’s state of motion, yet there is no unbalanced force to change your own state of motion. Thus, you continue in motion, sliding along the seat in forward motion.

We can think of this law as preserving the status quo of motion. Newton’s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity, either a change in magnitude or direction. An object sliding across a table or floor slows down due to the net force of friction acting on the object.