Science Scene - Dog Shake Geekiness :o)

A Georgia Institute of Technology team built a mathematical model of the processes involved, reasoning that surface tension between the water and the dog's hair is what keeps the dog wet. Overcoming that tension requires a centripetal force that exceeds it.

As centripetal force varies with distance from the centre of the creature, its radius is therefore crucial to work out the speed of the oscillations. The team arrived at an equation that calculates the frequency of that oscillation as R^0.5.

To test that hypothesis, the team filmed a wide range of dogs shaking, and used the images to calculate the period of oscillation. For a labrador retriever, that turned out to be 4.3 Hz. He then expanded the search, filming animals as small as mice (27 Hz) and as large as bears (4 Hz).

So the bigger the animal, the slower it can shake to achieve comparable drying, but the relationship isn’t linear. Instead, it approaches a limit of 4 Hz as an animal grows in size.

Please, Do Not Try This At Home :o)

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