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A wrist movement is not always a step

A step counter receives motion measurements, not a label saying “step.” Its software has to look for patterns and decide which movements belong in the count.

3–7 min

Questions you could explore

  • What would a false step look like in motion data?
  • How might filtering out false steps also hide some real ones?

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Engineering and inventions

How GPS finds you, and fixes its clock

Your phone can work out where it is by listening to signals from far above Earth. But turning a signal's travel time into a distance also creates a clock problem: the receiver must account for its own timing error.

5–7 min

How GPS finds you, and fixes its clock

Engineering and inventions5–7 minYour phone can work out where it is by listening to signals from far above Earth. But turning a signal's travel time into a distance also creates a clock problem: the receiver must account for its own timing error.

Engineering and inventions

Across an ocean inside a fiber-optic cable

A message crossing an ocean can travel through glass fibers lying on the seabed. The light inside, the layers around it, and the equipment along the route each solve a different problem.

8–10 min

Across an ocean inside a fiber-optic cable

Engineering and inventions8–10 minA message crossing an ocean can travel through glass fibers lying on the seabed. The light inside, the layers around it, and the equipment along the route each solve a different problem.

Engineering and inventions

Bicycle gears and the distance of one pedal turn

Pedaling a bicycle once around in a low gear moves you a short distance with an easy push; pedaling once in a high gear sends you much farther down the road. The ratio of teeth on the front chainring to the rear sprocket explains how a simple chain drive trades pedaling force against distance traveled.

3–5 min

Bicycle gears and the distance of one pedal turn

Engineering and inventions3–5 minPedaling a bicycle once around in a low gear moves you a short distance with an easy push; pedaling once in a high gear sends you much farther down the road. The ratio of teeth on the front chainring to the rear sprocket explains how a simple chain drive trades pedaling force against distance traveled.

A wrist movement is not always a step | Speech Topic | speaking.app