Newton's Second Law of Motion

How do unbalanced forces affect the motion of an object? An unbalanced force causes an object's velocity to change. In other words, the object accelerates. For example, you apply a net force to a ball when you throw it. The harder you throw, the more the ball accelerates. In fact, the acceleration of the ball is directly proportional to the net force acting on it. If you double the force, the acceleration of the ball doubles as well. Newton also learned that the acceleration of an object depends upon its mass. Mass is a measure of the inertia of an object and depends on the amount of matter the object contains.

According to Newton's second law of motion, the acceleration of an object is equal to the net force acting on it divided by the object's mass. Thus, doubling the mass of an object cuts its acceleration in half. Newton was able to put these ideas into a single formula.