Action-Reaction
Summary: Newton’s third law principle: every force has an equal and opposite counterpart. Tags: concepts physics forces Created: 2026-05-03T00:00:00Z Last Updated: 2026-05-03T00:00:00Z
Content
Action-reaction refers to Newton’s third law of motion: for every action force, there is an equal and opposite reaction force. These forces always act on different objects and are part of an interaction pair.
Key points:
- Forces are equal in magnitude, opposite in direction
- They act on different objects (so they do not cancel)
- Both forces arise simultaneously from the interaction
Examples:
- Rocket thrust: engine pushes exhaust down (action), exhaust pushes rocket up (reaction)
- Walking: foot pushes ground back, ground pushes foot forward