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Watch this one together

~5 min · materials: optional adult-supervised follow-up: two safe interlocking toy gears of different sizes; no suspended weights required

Can the tiny fast output start the same heavy crate as the big slow output?

A bicycle feels completely different after a gear shift even though the same rider is still supplying the input.

Talk about it

  • Turn two toy gears slowly and count how many teeth pass the contact on each side.
  • Before the book's load test, list what the turning-speed pages proved and what remains unknown.
  • After the reveal, name every variable the matched boxes kept the same.
Watch it together

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