FAA Powerplant Written Practice Test

According to Newton's third law of motion, what is stated?

1. Every action has a cause

2. For every action there is an equal and opposite reaction

3. Mass is a fundamental property of motion

4. For every force, there is a counterforce

The correct answer is: For every action there is an equal and opposite reaction

Newton's third law of motion articulates that for every action, there is an equal and opposite reaction. This principle means that forces always occur in pairs; when one object exerts a force on a second object, the second object simultaneously exerts a force of equal magnitude but in the opposite direction on the first object. This law is fundamental in understanding how objects interact in terms of motion and stability. For instance, when an aircraft engine expels exhaust gases backwards, the engine experiences a forward thrust due to this reaction force, propelling the aircraft forward. Understanding this concept is crucial in aviation and powerplant mechanics, as it helps explain how engines generate thrust, and thus relates directly to performance and efficiency. The other options provided touch on fundamental physics concepts, but they do not accurately capture the essence of Newton's third law.