What does Newton's Third Law state?

Newton's Third Law states that for every action, there is an equal and opposite reaction. This law highlights the fundamental principle that forces always occur in pairs. When one object exerts a force on a second object, the second object exerts a force of equal magnitude, but in the opposite direction, back onto the first object. This principle is essential in understanding interactions in mechanics, as it explains how objects move in response to forces acting upon them.

For example, when you push against a wall, you exert a force on the wall, and the wall exerts an equal force back on you. This is not just a conceptual idea; it activates throughout various phenomena in physics, from the way rockets propel themselves by expelling gas downwards to how animals move by pushing against the ground.

The other options denote other principles of physics. The statement about objects in motion staying in motion refers to Newton's First Law, which deals with inertia, while the force-mass-acceleration relationship describes Newton's Second Law. Finally, the conservation of energy pertains to the principles of thermodynamics and is unrelated to Newton's laws. Recognizing these distinctions helps in grasping the broader concepts in physics.