AEMCA Practice Exam

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

1. Motion is directly proportional to speed.

2. The total force is equal to mass times acceleration or deceleration.

3. Frictional force will always oppose motion.

4. Matter cannot change its state of motion without a net force.

The correct answer is: The total force is equal to mass times acceleration or deceleration.

Newton's second law of motion fundamentally states that the total force acting on an object is equal to the mass of that object multiplied by its acceleration. This relationship can be expressed mathematically as F = ma, where F represents the total force applied, m is the mass of the object, and a is the acceleration produced. This law explains how the motion of an object changes when a net external force is applied. In practical terms, it means that if you want to increase the velocity of an object (accelerate it), you must apply a greater force to overcome its inertia, which is directly related to its mass. This principle is central to understanding dynamics and is critical in predicting how an object will move when forces are applied. The other options discussed do not accurately reflect Newton's second law. The notion that motion is directly proportional to speed is too general and does not capture the specific relationship of force, mass, and acceleration. Frictional forces do indeed oppose motion, but this concept relates more to forces acting on objects rather than the fundamental law of motion. Lastly, while the statement about matter not changing its state of motion without a net force hints at the first law of motion (the law of inertia), it does not encompass the direct relationship