What is Hooke's law?

Hooke's law: F = k × x. A spring stretches in proportion to the force pulling it: twice the pull, twice the stretch. The number that links them, k, says how stiff the spring is, and the rule holds until you stretch it past its elastic limit.

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Chapters in this interactive model

1. Twice the pull, twice the stretch: Force = stiffness × stretch. Hang masses on springs and watch it hold.
2. Springs that weigh and push back: A market balance and a click pen: both trust F = k × x.
3. Springs that carry you: Car suspension and a bungee cord: stretch, store, give it back.
4. Springs that sing: A harmonium reed and a guitar string are springs that keep time.
5. Past the elastic limit: Steel that stays stretched, rubber that curves, and a myth about stiff springs.