Physics
Forces, energy and motion — a handful of laws that explain almost everything.
Key ideas
Newton in three lines
Things keep doing what they are doing unless a force acts (1st). Force changes motion: F = ma (2nd). Forces come in equal and opposite pairs (3rd).
Energy changes form, never total
A falling ball trades height (potential energy, mgh) for speed (kinetic energy, ½mv²). Add up every form and the total never changes — that is conservation of energy.
Circuits in one sentence
Voltage pushes, resistance resists, current is what flows: V = IR. Double the voltage and current doubles; double the resistance and it halves.
Flashcards
Quick quiz
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A 2 kg cart accelerates at 3 m/s². The net force on it is…
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