daily.surf

Ocean · Puzzle #2 · Thursday, October 1

Ocean: the answers

Four questions, each with one true number. Here they are with their answers, how to reason each one out, and where the number comes from. Play today's Ocean.

  1. 1. In open ocean water 15,000 feet deep, about how fast does a tsunami travel, in miles per hour?

    Photo: NOAA, Public domain

    The answer: about 475 miles per hour. That is jet-airliner speed; near shore the waves slow to roughly 20 or 30 miles per hour as they pile up.

    Napkin math: Tsunami speed is the square root of depth times gravity: sqrt(15,000 x 32.2) is about 700 feet per second.

    Source: NOAA / National Weather Service U.S. Tsunami Warning System, Tsunami Frequently Asked Questions

  2. 2. A female Atlantic bluefin tuna can release up to how many eggs in a year?

    Photo: Unknown authorUnknown author, Public domain

    The answer: up to 10 million eggs. Bluefin spawn mainly in the Gulf of America, and their eggs hatch in about two days.

    Napkin math: Fish that scatter tiny eggs in open water and give no care make up for terrible odds with sheer numbers: think millions.

    Source: NOAA Fisheries, Western Atlantic Bluefin Tuna

  3. 3. In 1947, Thor Heyerdahl sailed the balsa raft Kon-Tiki from South America to Polynesia. About how many miles did the raft travel across the Pacific?

    Photo: Wikipek, CC0

    The answer: about 5,000 miles (8,000 km). Six men and a parrot set sail from Callao, Peru, on 28 April 1947, and the raft is now displayed at the Kon-Tiki Museum in Oslo.

    Napkin math: Peru to the Tuamotu Islands spans a big chunk of the Pacific, roughly the width of the United States and then some.

    Source: Kon-Tiki Museum, Kon-Tiki Museum (English home page)

  4. 4. What is the Guinness World Record for the most surfboards stacked on top of a single car (which then drove 100 feet)?

    Photo: Osamu Uchida from osaka, japan, CC BY 2.0

    The answer: 282 surfboards. A group of surfers set the record near Santa Barbara, California, in 1998, stacking the boards on a Humvee.

    Napkin math: A surfboard lying flat is about 3 inches thick, so a stack a few dozen feet tall on the roof would hold a couple hundred boards.

    Source: Guinness World Records, Most surfboards stacked on a car

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