Newton's Third Law

This lesson covers action–reaction pairs, how they involve the same type of force on different objects, and common examples, as required by the Edexcel GCSE Combined Science specification (1SC0). Newton's Third Law is one of the most frequently misunderstood ideas in physics, so understanding it clearly will give you an advantage in the exam.

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Newton's Third Law

Newton's Third Law states: When two objects interact, the forces they exert on each other are equal in magnitude, opposite in direction, and of the same type.

This is sometimes summarised as: "Every action has an equal and opposite reaction." However, this short version can be misleading, so let us look at the full meaning.

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Key Features of Third Law Pairs

Every Newton's Third Law pair has four essential features: