Praxis Elementary Education: Three-Subject Bundle – Science (5905) Practice Test

Action and reaction forces come as a pair that are equal in strength and opposite in direction. This principle is Newton's Third Law, often called the Law of Interaction. When two objects interact, they push on each other with equal force in opposite directions, and each force acts on the different object. For example, pushing against a wall sends a backward push on the wall and a forward push on your hand; a rocket expels exhaust backward, and the exhaust pushes the rocket forward. The forces are paired and simultaneous, yet they don’t cancel because they don’t act on the same object. The other laws describe different ideas: the first law is about objects maintaining motion or rest in the absence of net force; the second law links net force to how much an object accelerates; gravitation describes how masses attract each other.