According to Newton's Law of Motion, how is acceleration produced?

Acceleration is produced when a force acts on a mass, which is a principle derived from Newton's Second Law of Motion. This law states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. In practical terms, this means that if you apply a greater force to an object, it will accelerate more, provided its mass remains constant. Conversely, for a given force, an increase in mass will result in a smaller acceleration.

Considering this context, the correct answer highlights the fundamental relationship between force and motion as defined by Newton's laws. The other options present concepts that do not directly align with the definition of acceleration as it relates to mass and force. An increase in mass would not produce acceleration on its own without an accompanying force. The application of heat pertains more to thermal energy rather than directly influencing motion. Changing direction refers to altering the velocity vector of an object but does not intrinsically imply that acceleration is produced without some form of force acting on that object. Thus, understanding the relationship encapsulated by Newton's Second Law provides a clear foundation for why a force acting on a mass is essential for producing acceleration.