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How can a mechanical watch keep time without electricity?

A mechanical watch needs both a supply of energy and a way to release it in controlled steps. A wound mainspring provides the energy; a moving balance and escapement help regulate the motion that eventually reaches the hands.

3–7 min

Questions you could explore

  • Why would a spring and some gears be insufficient on their own?
  • How do the escapement and oscillator regulate the release of a watch spring's energy?

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