Newton's third law of motion states that for every action, there is an equal and opposite reaction. When applied to a rifle firing a bullet, we can observe the following:
Action: When the trigger of the rifle is pulled, a chemical reaction occurs within the firearm's chamber, causing the expanding gases to propel the bullet forward.
Reaction: As the expanding gases push the bullet forward, an equal and opposite force is applied to the rifle itself, pushing it backward. This force is commonly referred to as the "recoil" or "kick" of the firearm.
The rifle and bullet experience forces of the same magnitude but in opposite directions. The bullet accelerates forward due to the force generated by the expanding gases, while the rifle recoils backward due to the reaction force.
It's worth noting that the acceleration of the bullet and the recoil of the rifle are not necessarily equal in all aspects. The bullet's acceleration depends on its mass and the force applied by the expanding gases, while the recoil of the rifle depends on the mass of the rifle itself. Factors such as the design of the firearm, weight distribution, and the amount of energy transferred to the bullet can influence the perceived recoil and how it affects the shooter.