YFC Science Team6 min read
First law — balanced forces
If forces are balanced, velocity stays constant. A book on a table stays still because gravity and the normal force cancel out.
Second law — F = ma
Acceleration depends on force and mass. Doubling force doubles acceleration; doubling mass halves it. Always state units: N, kg, m/s².
Third law — action and reaction
Forces always come in pairs on different objects. A swimmer pushes water backward; water pushes the swimmer forward.
Quick answers
What is the most common Newton's law exam mistake?
Confusing action-reaction pairs as acting on the same object. They always act on different objects.
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