Newton's Third Law
Newton's third law states that for every action, there is an equal and opposite reaction acting on a different body.
Practice This ConceptMain explanation
Teacher explanation
Action and reaction forces are equal in magnitude and opposite in direction, but they act on two different objects. Therefore, they do not cancel each other on the same body.
Example
When a swimmer pushes water backward, the water pushes the swimmer forward with an equal opposite force.
Simple analogy
Third law pairs are equal, opposite, and on different bodies.
Common confusion
Students often say action and reaction cancel, but they act on different bodies, so they cannot cancel on one body.
Exam tip
Always name both bodies in the action-reaction pair.
Study the newton's third law diagram carefully
Use the labelled diagram to keep newton's third law clear in short answers and revision.
What this diagram makes clear
This diagram keeps the labels and direction of newton's third law in the right order.
Where this helps in exams
Use this for labelled diagram work and short exam answers on newton's third law.
Revision cue
Revise newton's third law through the labels before writing the answer.
Answer writing and exam use
1-mark use
Write the exact meaning of newton's third law in one clean line.
2-mark use
Define newton's third law and add one example or condition.
3-mark use
Explain newton's third law, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
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