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

with Khalid Robinson

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

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

Hey I’m Khalid and today with About.com we are going to discuss Newton’s Third 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 Action-Reaction Law

Newton’s third law of motion states, “When two bodies interact by exerting force on each other, these action and reaction forces are equal in magnitude, but opposite in direction.”  More commonly this is stated, “ for every action, there is an equal and opposite reaction”, and is known as the action-reaction law.

The concept is that for every exerted force (action), there is an opposite force (reaction) being equally exerted.

### How the Third Law of Motion is Observed

This can also be observed while standing here.  It might seems that there is only one force being exerted here, my feet pressing down on the floor, but in order not to fall through the floor, it must exert a force upon me.  So, while my foot is exerting a downward force onto the floor, the floor is exerting an equal and opposite upward force onto my foot, the result of which allows me to remain standing.