Final answer:
According to Newton's third law, when a cannon fires a cannonball, there's an equal and opposite reaction, causing the cannon to recoil. The acceleration will be greater for the less massive object, the cannonball, unless both have equal mass, then both would accelerate at the same rate but in opposite directions.
Step-by-step explanation:
Newton's third law of motion states that for every action, there is an equal and opposite reaction. When a cannon launches a cannonball, the cannon exerts a force on the cannonball to propel it forward. In response, the cannonball exerts an equal and opposite force on the cannon, pushing it backward. This is commonly referred to as the cannon's recoil.
The acceleration of the cannonball and the cannon depend on their respective masses, due to Newton's second law of motion, which relates acceleration to force and mass (F = ma). The cannonball, usually having less mass compared to the cannon, will have a larger acceleration. If the cannonball were just as massive as the cannon, they would both accelerate at the same rate, but in opposite directions. However, since the cannon is anchored or has much more friction with the ground compared to the airborne cannonball, the visible movement (recoil) of the cannon will be much less.