The law that describes acceleration as proportional to the resultant force acting on a mass is which law?

• A. Newton's First Law of Motion
• B. Newton's Second Law of Motion
• C. Newton's Third Law of Motion
• D. Law of Thermodynamics

Answer: (B)

The movement of a mass responds to the net force acting on it. The law says the acceleration you get is proportional to the resultant (net) force and inversely proportional to the mass. In practice, this means doubling the net force doubles the acceleration for the same mass, while doubling the mass halves the acceleration for the same force. The direction of the acceleration matches the direction of the net force. If there’s no net force, there’s no acceleration, and the object keeps moving at whatever velocity it has. This relationship is written as F = ma, linking force, mass, and acceleration. The other options describe different ideas: inertia with no net force, action–reaction pairs, and energy/heat principles, not this direct force–motion connection.