What is described by Newton's second law of motion?

Newton's second law of motion fundamentally describes the relationship between an object's mass, the net force acting upon it, and its acceleration. This law states that when an unbalanced force acts on an object, the acceleration of that object is directly proportional to the net force acting on it and inversely proportional to its mass. This can be expressed in the equation F = ma, where F represents the net force, m is the mass of the object, and a is the acceleration produced.

This principle explains how varying the force acting on an object impacts its motion, elucidating that a greater force will yield a higher acceleration if the mass remains constant. Conversely, if the mass increases while the force is constant, the acceleration will decrease. This law is foundational in both classical mechanics and in understanding how objects respond to forces in various situations.

The other choices represent different laws or concepts in physics. The first describes Newton's third law of motion, which deals with action-reaction pairs. The third refers to Newton's first law, emphasizing inertia. The last choice pertains to the law of universal gravitation, which explains the attraction between masses. Understanding these distinctions enhances comprehension of the specific nature of each of Newton's laws.