Which law describes the action-reaction forces on two interacting objects?

Which law describes the action-reaction forces on two interacting objects?

• A. Newton's First Law of Motion
• B. Newton's Second Law of Motion
• C. Newton's Third Law of Motion
• D. The Law of Gravity

Answer: (C)

Action and reaction forces come in pairs that are equal in strength but opposite in direction and act on two interacting objects. This is Newton's Third Law of Motion. Because the forces act on different objects, they do not cancel each other out even though they have the same magnitude. A simple example is when you push against a wall: your hand pushes the wall, and the wall pushes back on your hand with the same force in the opposite direction. Similarly, firing a rocket or gun sends ejecta one way, while the reaction force pushes the rocket in the opposite direction. The other ideas describe different principles—inertia and how acceleration relates to force, and gravity as a separate force law—so they don’t describe the action-reaction pair.

Action and reaction forces come in pairs that are equal in strength but opposite in direction and act on two interacting objects. This is Newton's Third Law of Motion. Because the forces act on different objects, they do not cancel each other out even though they have the same magnitude. A simple example is when you push against a wall: your hand pushes the wall, and the wall pushes back on your hand with the same force in the opposite direction. Similarly, firing a rocket or gun sends ejecta one way, while the reaction force pushes the rocket in the opposite direction. The other ideas describe different principles—inertia and how acceleration relates to force, and gravity as a separate force law—so they don’t describe the action-reaction pair.