Analyzing Formulas & How Variables Relate

Speed versus Size

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Speed versus Size

Vincent Strouhal, a physicist from Czechoslovakia, discovered a number that compares the speeds of flying animals with respect to their wing sizes. To calculate the Strouhal number, you multiply the wing flapping frequency by the distance between the tip of the wing at its highest and lowest points, and then divide the result by the animal’s cruising speed.

  • How does the wing-flapping frequency of the hummingbird compare to that of the albatross?
  • About how many wing flaps per second do you think the hummingbird and the albatross make when flying at cruising speed?