F. G. Grisley, Author at New ÐÓ°ÉÔ­´´ Science news and science articles from New ÐÓ°ÉÔ­´´ Fri, 10 Sep 1993 23:00:00 +0000 en-US hourly 1 https://wordpress.org/?v=7.0.1 242057827 Letters: In a spin /article/1830055-letters-in-a-spin-2/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 10 Sep 1993 23:00:00 +0000 http://mg13918906.300 After a bath, remove the plug and let the usual vortex develop. Dip
a finger in the centre of the bath and stir gently in the opposite direction
for a few seconds only.

Very soon, the vortex at the plug hole will weaken and disappear. A
new vortex will then establish itself in the opposite direction.

The angular momentum of the first vortex is obviously very much greater
than that of the induced rotation in the centre of the bath. Yet the latter
overcomes the former.

It is an elegant demonstration of the ‘butterfly effect’. It is said
that the flap of a butterfly’s wing in China can affect our weather two
weeks later. Although many people may question this, the bath vortex is
demonstrably true and only takes about a minute.

I am also struck by the visual similarity with the Lorenz attractor.
Is there a correlation?

F. G. Grisley Barry, Glamorgan

]]> 1830055 Letters: Sound query /article/1829165-letters-sound-query/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 23 Apr 1993 23:00:00 +0000 http://mg13818707.000 I have a query concerning polystyrene plastic. This polymer makes a
distinctive ‘clank’, or tinkling sound when dropped on a hard surface. It
does this whether in the form of a solid, an alloy (ABS) or, remarkably,
an expanded foam.

Is there a scientific reason for this, and are there other plastics
which may be identified by their distinctive sounds?

F. G. Grisley Barry, Glamorgan

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