What does Newton's Second Law of Motion describe?

Newton's Second Law of Motion describes the fundamental relationship between force, mass, and acceleration, which is articulated in the equation F = ma. This law demonstrates that the force acting on an object is equal to the mass of that object multiplied by its acceleration. This means that the greater the force applied to an object, the more it will accelerate, which is also dependent on the object's mass. The practical implication of this law is critical in the fields of physics and engineering, as it explains how varying forces can affect an object's motion.

The other choices relate to different concepts in physics but do not encapsulate the specific essence of Newton's Second Law. For instance, while one choice mentions forces acting on resting objects, it does not address the interaction of force and motion as described by the law. Another option discusses the impact of gravity specifically, which is a particular case rather than the broader principle that Newton's Second Law covers. Discussing the behavior of objects in motion would be more aligned with Newton's First Law or have broader implications outside of just force, mass, and acceleration. Thus, the relationship between these variables is what makes option B the correct choice regarding Newton's Second Law of Motion.