# Newton's Law

## Newton’s First Law

Newton’s First Law states: an object moves in a straight line and at constant speed except to the extent that it interacts with other objects

Meaning with no interaction, a moving object will continue to move in a straight line

This is also known as The Law of Inertia

inertia: in a sense, the resistance of change in motion

example: bowling ball vs ping pong ball – which one takes more force to move?

## Newton’s Second Law

Newton’s Second Law states: the momentum of a system does not change unless a net external force acts on it

This is also known as The Momentum Principle

Click the link above for an interactive browser exercise to practice with forces.

## Newton’s Third Law

Newton’s Third Law states: for every action, there is an equal and opposite reaction

reciprocity: the idea that the force that object 1 exerts on object 2 is equal and opposite to the force that object 2 exerts on object 1