A cannon recoiling after firing a shot is an example of:

Newton's Third Law states that every action has an equal and opposite response. Some instances of Newton's 3^rd Law include gun firing, in which the reaction force propels the gun rearward, and When a rocket tool takes off, the gas in its rear exhausts. 

The rocket is propelled upward by the reaction force. Energy cannot be generated or destroyed, according to the Law of Conservation of Energy. 

Newton's First Law of Motion states that every object remains at rest or in uniform motion in a straight line unless pushed to alter its condition by forces imprinted on it. This is often referred to as the Law of Inertia.