Which statement expresses Newton's Third Law of Motion?

Which statement expresses Newton's Third Law of Motion?

• A. For every action there is an equal and opposite reaction.
• B. An object in motion will remain in motion unless acted upon by another force.
• C. Force equals mass times acceleration.
• D. A damper dissipates energy.

Answer: (A)

When one body pushes on another, the other body pushes back with a force that is exactly the same in strength but opposite in direction. This is Newton's Third Law: action-reaction pairs are equal in magnitude, opposite in direction, and act on two different objects at the same time. This explains everyday and engineering phenomena, like a rocket expelling exhaust backward to move forward or a hand feeling a backward push when you press against a wall. The forces cancel only if you look at a single object, but they don’t cancel the motion of the two bodies involved because they act on different objects. The other statements describe different ideas: inertia from Newton’s First Law, F = m a from Newton’s Second Law, and energy dissipation by a damper, which is not about action–reaction forces.

When one body pushes on another, the other body pushes back with a force that is exactly the same in strength but opposite in direction. This is Newton's Third Law: action-reaction pairs are equal in magnitude, opposite in direction, and act on two different objects at the same time. This explains everyday and engineering phenomena, like a rocket expelling exhaust backward to move forward or a hand feeling a backward push when you press against a wall. The forces cancel only if you look at a single object, but they don’t cancel the motion of the two bodies involved because they act on different objects. The other statements describe different ideas: inertia from Newton’s First Law, F = m a from Newton’s Second Law, and energy dissipation by a damper, which is not about action–reaction forces.