Final answer:
Object B's acceleration is one-third of object A's because it has three times the mass and the same force is applied, according to Newton's second law (F=ma) which states that acceleration is inversely proportional to mass.
Step-by-step explanation:
When the same net force is applied to two objects with different masses, their accelerations will differ. According to Newton's second law of motion, force equals mass times acceleration (F=ma). If object B is three times more massive than object A, and the same force is applied to both, then using the formula for acceleration (a = F/m), it is clear that object B's acceleration will be one-third of object A's because B has three times the mass of A. Thus, the acceleration of object B compared to object A is one-third.
To put this into context with Newton's laws, if object A has a mass of m and experiences an acceleration of a, then object B with a mass of 3m under the same force would have an acceleration of (1/3)a. The example grasps the concept that more massive objects require more force to achieve the same acceleration, or conversely, with the same force applied, more massive objects will have a lower acceleration.