What is Newton's second law of motion?

What is Newton's second law of motion?

• A. An object will stay at rest or move at a constant velocity unless acted upon by a net external force.
• B. An object's acceleration is proportional to the net force acting on it and in the direction of the force.
• C. For every action there is an equal and opposite reaction.
• D. F = m a.

Answer: (B)

Acceleration happens when a net external force acts on an object. The bigger the net force, the greater the acceleration, and the bigger the mass, the smaller the acceleration for the same force. The acceleration points in the same direction as the net force. This captures the essence of Newton's second law: the net force on a body determines its acceleration, with mass setting how much acceleration results. In formula form, F_net = m a, so doubling the net force (with mass fixed) doubles acceleration, and doubling the mass (with force fixed) halves acceleration. Remember to use the net force—the vector sum of all forces—since multiple forces combine to produce the actual effect. The statement that acceleration is proportional to the net force and lies in its direction conveys this relationship most directly.

Acceleration happens when a net external force acts on an object. The bigger the net force, the greater the acceleration, and the bigger the mass, the smaller the acceleration for the same force. The acceleration points in the same direction as the net force. This captures the essence of Newton's second law: the net force on a body determines its acceleration, with mass setting how much acceleration results. In formula form, F_net = m a, so doubling the net force (with mass fixed) doubles acceleration, and doubling the mass (with force fixed) halves acceleration. Remember to use the net force—the vector sum of all forces—since multiple forces combine to produce the actual effect. The statement that acceleration is proportional to the net force and lies in its direction conveys this relationship most directly.