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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

Questions you could explore

  • How do distances from several satellites narrow down a position?
  • Why does the receiver need to solve for time as well as location?

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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.

Engineering and inventions

Induction cooking heats the pan itself

An induction coil uses a changing magnetic field to generate heat in compatible cookware. The choice of pan matters because the heat is not simply conducted from a conventional burner. Explore how the energy reaches the cookware, and why the cooktop surface can still become hot from the pan.

3–5 min

Induction cooking heats the pan itself

Engineering and inventions3–5 minAn induction coil uses a changing magnetic field to generate heat in compatible cookware. The choice of pan matters because the heat is not simply conducted from a conventional burner. Explore how the energy reaches the cookware, and why the cooktop surface can still become hot from the pan.

How GPS finds you, and fixes its clock | Speech Topic | speaking.app