Newton's second law of motion states that the acceleration of a system is related to the net external force and the mass in which way?

1. Acceleration is directly proportional to and in the same direction as the net external force. 2. Acceleration is inversely proportional to the mass of the system. 3. Combining the two gives acceleration equal to the net external force divided by the mass. 4. Rearranged, that is the familiar statement that net force equals mass times acceleration. _Source: OpenStax College Physics (CC BY 4.0), Ch 4 "Dynamics: Force and Newton's Laws of Motion", section 4.3 Newton's Second Law of Motion: Concept of a System_