Back to topics

Shark-skin texture and the conditions for lower drag

Shark skin's tiny structures interact with flowing water and a moving body. Experiments comparing rigid and flexible surfaces found that configuration mattered. Copying a biological texture is only part of copying the system that makes it useful.

3–7 min

Questions you could explore

  • Why might a texture behave differently on a rigid plate and on a flexible surface moving through water?
  • How would the size and orientation of surface ridges affect a drag comparison?

Start reading

Ready to try your ideas aloud?

Your topic carries over. Record up to 2½ minutes, depending on your plan.

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.

Shark-skin texture and the conditions for lower drag | Speech Topic | speaking.app