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# Video:Quick Tip: Newton's First Law of Motion

with Khalid Robinson

Newton's First Law of Motion is also known as the Law of Inertia. Watch this About.com video to see how this physics law is demonstrated.See Transcript

## Transcript:Quick Tip: Newton's First Law of Motion

Hey I’m Khalid and today with About.com we are going to discuss Newton’s First Law of Motion.

In 1687, Sir Isaac Newton published “The Mathematical Principles of Natural Philosophy” in which he defined the physics of motion.  From this there were three laws that became cornerstones of classical physics.

### The Law of Inertia

Newton’s first law of motion is, “Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.” This is most commonly stated as, “Objects at rest stay at rest or objects in motion stay in motion (with the same direction and speed) unless acted on by an unbalanced force.”  This can also be called the Law of Inertia.

### How the First Law of Motion is Observed

To understand this, let’s look at this ball sitting on a table.  If nothing hits this ball (if no force acts upon it), it will stay in its exact spot forever.

We can also see Newton’s first law of motion at work when trying to get ketchup out of a bottle.  Applying force to the bottle in the form of shaking it, causes the bottle to apply the same force to the ketchup.  However, when we halt the motion of the bottle, the ketchup (which we are not stopping) continues on with the same force and in the same direction until a force acts on it.  Thus, the ketchup flies out of the bottle.