Which statement is an expression of Newton's Third Law?

Which statement is an expression of Newton's Third Law?

• A. An object at rest stays at rest
• B. For every action there is an equal and opposite reaction
• C. Force equals mass times acceleration
• D. The planets orbit the Sun

Answer: (B)

Newton's Third Law is about forces that occur in pairs during interactions: when one object pushes on another, the second object pushes back with the same strength in the opposite direction. The statement that “For every action there is an equal and opposite reaction” directly expresses that paired, balanced interaction. That idea is why it’s the best match. For example, when you push against a wall, the wall pushes back with an equal force in the opposite direction, which is why you can feel the resistance. A rocket launches by expelling exhaust backward, and in response the rocket is pushed forward. Walking works the same way: your foot pushes the ground backward, and the ground pushes you forward. The other statements describe different ideas: an object at rest staying at rest reflects inertia (the First Law), force equals mass times acceleration is Newton’s Second Law, and planets orbiting the Sun is a gravitational motion description, not an action-reaction pair.

Newton's Third Law is about forces that occur in pairs during interactions: when one object pushes on another, the second object pushes back with the same strength in the opposite direction. The statement that “For every action there is an equal and opposite reaction” directly expresses that paired, balanced interaction.

That idea is why it’s the best match. For example, when you push against a wall, the wall pushes back with an equal force in the opposite direction, which is why you can feel the resistance. A rocket launches by expelling exhaust backward, and in response the rocket is pushed forward. Walking works the same way: your foot pushes the ground backward, and the ground pushes you forward.

The other statements describe different ideas: an object at rest staying at rest reflects inertia (the First Law), force equals mass times acceleration is Newton’s Second Law, and planets orbiting the Sun is a gravitational motion description, not an action-reaction pair.