Final answer:
The change in the motion of objects depends on their mass and the applied net force, concepts fundamental to Newton's second law. Mass, which denotes inertia, along with net force, affects an object's acceleration, making them critical in understanding motion.
Step-by-step explanation:
The change in the motion of Object A or Object B depends on their mass and the net force applied to them. This relationship is described by Newton's second law, which states that the rate of change of momentum of a body is directly proportional to the net external force applied to it, and this change occurs in the direction of the net force. According to this law, inertia, or an object's ability to resist changes to its motion, is measured by its mass.
Furthermore, it is important to understand that mass and weight are not the same. Mass is a measure of the amount of 'stuff' in an object and does not vary with location, while weight is the force of gravity acting on that mass and can vary depending on the object's location in the universe. For example, the mass of an object is the same on Earth, in orbit, or on the surface of the Moon.
To summarize, both mass—largely a measure of inertia—and the applied net force are key to understanding changes in motion. When analyzing these effects, free-body diagrams can help visualize the forces in play.