Newton's First Law (Inertia)
Newton's first law states that an object remains at rest or in uniform straight-line motion unless acted upon by an unbalanced external force.
Practice This ConceptMain explanation
Teacher explanation
This law explains inertia, the tendency of a body to resist change in its state of rest or motion. Greater mass means greater inertia, so heavier objects resist change more.
Example
Passengers jerk forward when a moving bus suddenly stops because their bodies tend to continue moving forward due to inertia.
Simple analogy
Inertia means an object wants to continue its present state.
Common confusion
Students often say inertia is a force, but inertia is a property of matter, not a force.
Exam tip
In seat-belt questions, mention inertia of motion and sudden stopping of the vehicle.
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Revision cue
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Answer writing and exam use
1-mark use
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2-mark use
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3-mark use
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