Which statement expresses Newton's Second Law of Motion?

Which statement expresses Newton's Second Law of Motion?

• A. An object at rest tends to stay at rest, unless acted upon by a net external force.
• B. Force equals mass times acceleration.
• C. For every action there is an equal and opposite reaction.
• D. A frequency with which a structure can resonate.

Answer: (B)

Newton's Second Law describes how a net external force changes the motion of a body, with acceleration arising in proportion to the net force and inversely to the mass. In its common form, the relationship is F = m a, where force is a vector, mass is a scalar, and acceleration has the same direction as the net force. This means if you push harder (larger force) you accelerate more, and if the mass is larger, the same force produces a smaller acceleration. When multiple forces act, you sum them to get the net force that drives the acceleration. The statement that force equals mass times acceleration captures this direct link between force and motion, which is why it is the correct expression of Newton's Second Law. The other options reflect different ideas: one describes inertia (an object at rest tends to stay at rest), another is Newton's Third Law (every action has an equal and opposite reaction), and the last refers to resonance frequency, not a fundamental law of motion.

Newton's Second Law describes how a net external force changes the motion of a body, with acceleration arising in proportion to the net force and inversely to the mass. In its common form, the relationship is F = m a, where force is a vector, mass is a scalar, and acceleration has the same direction as the net force. This means if you push harder (larger force) you accelerate more, and if the mass is larger, the same force produces a smaller acceleration. When multiple forces act, you sum them to get the net force that drives the acceleration.

The statement that force equals mass times acceleration captures this direct link between force and motion, which is why it is the correct expression of Newton's Second Law. The other options reflect different ideas: one describes inertia (an object at rest tends to stay at rest), another is Newton's Third Law (every action has an equal and opposite reaction), and the last refers to resonance frequency, not a fundamental law of motion.