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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.

12–15 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

Why does one pedal turn take you different distances?

Changing bicycle gears changes the relationship between your pedals and the rear wheel. The teeth on the chainring and sprocket help explain why the same turn of the pedals can produce a different distance along the road.

3–5 min

Why does one pedal turn take you different distances?

Engineering and inventions3–5 minChanging bicycle gears changes the relationship between your pedals and the rear wheel. The teeth on the chainring and sprocket help explain why the same turn of the pedals can produce a different distance along the road.

Engineering and inventions

How can an induction cooktop heat the pan itself?

An induction cooktop can heat compatible cookware without first making an element glow. A changing magnetic field transfers energy into the pan, making the choice of cookware part of how the system works.

3–5 min

How can an induction cooktop heat the pan itself?

Engineering and inventions3–5 minAn induction cooktop can heat compatible cookware without first making an element glow. A changing magnetic field transfers energy into the pan, making the choice of cookware part of how the system works.

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