Physics 11 · Physics · Lesson 4.3
The Third Law
- Level
- Grade 11
- Reading time
- 12 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Action–reaction pairs.
Concept preview
What you will be able to do
- 01State Newton's third law
- 02Identify action–reaction force pairs
- 03Explain why paired forces don't cancel
Newton's third law: for every action there is an equal and opposite reaction. If object A pushes on object B, then B pushes back on A with a force equal in size and opposite in direction. Forces always come in pairs — you cannot push on something without it pushing back on you.
School Plan
The Third Law
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