# misc.ience

## How fast to shake to get dry? Science answers…aimee whitcroftOct 21

It’s a difficult subject, this.

And probably too punworthy for me to be able to help myself (although I shall try).

Some enterprising scientists have discovered the optimal oscillation needed by a hairy beastie shaking itself dry.  And by oscillation, of course, I mean ‘shaking of the body’. Or, possibly, ‘booty’.

They filmed a bunch of dogs shaking themselves as a means of water dispersal*, and had  a look at the results, which for labrador retrievers was 4.3 Hz.

This led to a lovely model in which they hypothesized that the oscillation necessary is R^0.5, where R is the radius of the body**. Which means that smaller animals will have to shake faster.  A mouse must shake faster than, say, a woolly mammoth.

Of course, and as with all science, the prediction above needs to be tested, and this is what our friendly scientists did.  They looked at mice, cats, bears, and no doubt a plethora of other beasties, and found that yes, the larger the animal, the lower the Hz.

To be more specific, mice come in at 27 Hz, cats at 6Hz, and bears at a stunning 4 Hz.  (I still want to see a woolly mammoth shaking, for the humour/awe as well as the science)

They also found that the equation is a little different from that originally conceived, with the optimal oscillation being closer to R^0.75 = driest beastie possible.

Thought points:

How exactly does one define R?  Does it include or exclude fur?

To what practical use could we put this?  A device to optimally oscillate string mops?  How fast one should shake one’s head to dry our hair?  (Or, for that matter, how best to head bang to ensure maximum sweat coverage of those around one?)

Perhaps there’s a use for salad spinners?

And see?  I managed not to pun too much (she said drily)

UPDATE:

I clearly like things to do with fluid dynamics, given that I’ve also posted about teapots

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*One wonders if they also measured the oscillation frequency necessary to make any humans in the vicinity scream the loudest.

** Reasoning as follows, for those who’re interested.  Water is stuck to the animal’s fur due to surface tension between water and air.  In order for the water to become unstuck, enough centripetal force*** needs to be generated to overcome this.

*** Yes yes, I know.

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The arXiv article I based this on.  As usual, the authors of these articles are legendary in their ability to explain this sort of stuff.  Note their wonderfully facepalm-worthy use of ‘paws.

## Brilliant photos of small thingsaimee whitcroftOct 21

Being a large fan of all things small, particularly when one is able to take photos of them, I bring you this:

Credit: Jocelyn Chang. An image of a bryozoa, from the Nikon Small World competition (2010)

Yes, the results for this year’s Nikon Small World competition are in.  Each year, the competition takes in entries of the best microscopy on the web, and then hurls awards at the ones it likes the most.

Or something.

I remember spending hours happily closeted with a very large and expensive fluorescent  microscope, taking perdy pictures of the neural cells with which I was playing for my Honours degree.  At the time, my supervisor mentioned that microscopists were in increasing demand overseas, and whenever I see images like this, I wonder whether I should have become one of these.

After all, it’s photography with science.  Two of my bestest things.

UPDATE:

I also came across this fabulous video of an octopus being very balletic…