Physicsstop back in business

I have been rather conscious of my looonnnnggggg absence from the blogosphere. That really is down to other commitments getting in the way, and then falling out of the habit of blogging.  Hopefully this will be a restart. I have a good opportunity here – I have just started a period of study leave (what […]

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Modes of a square plate

Alison has drawn my attention to this video. It demonstrates vibrational modes of a square plate by using sand. At certain frequencies, there are well defined modes of oscillation, in which parts of the plate 'nodal lines' are stationary. The sand will find its way to these parts and trace out some lovely pictures.  Vibrational […]

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Managing ignition timing

I've just been at a great lecture by Peter Leijen as part of our schools-focused Osborne Physics and Engineering Day.   He's an ex-student of ours, who did electronic engineering here at Waikato – and graduated just a couple of years ago.  He now works in the automotive electronics industry. That's an incredibly quickly growing […]

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Seeing in the dark

No, nothing to do with carrots and vitamin A I'm afraid.  With dark evenings and mornings with us now :(, Benjamin's become interested in the dark. It's dark after he's finished tea, and he likes to be taken outside to see the dark, the moon, and stars, before his bath. "See dark" has become a […]

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Neurons or chickens?

Last weekend we had an expedition out to rural Waikato somewhere beyond Morrinsville (in torrential rain of course) to a chicken farm and bought a couple of young chickens. The idea is that they’ll give us an egg supply, and, if properly controlled (ha ha!) dig up the weeds, fertilize the garden etc. (Or, more […]

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Friction: Stick or Slip?

Going back to my last entry on the sliding car, it’s worth commenting a bit more on the nature of friction here. When a car goes round a corner, what prevents it from sliding is the friction between the tyres and the road. Tyres are unsurprisingly designed to be able to give a high frictional […]

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Schlieren imaging

I’ve been sent this link to a movie of a shock wave from a trombone.  You’ve got to feel sorry for the poor clarinetist who is sitting in front. This sort of thing can be done neatly with the method of schlieren imagaing. (See some more examples here) This is a ‘simple’ way of picking up […]

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Piezoelectricity

I went to a very informative seminar this morning by Peter Pott, of the Technical University, Darmstadt, Germany. He gave a very nice introduction to the world of piezoelectric devices. In short, a piezoelectric thing is something that acquires a voltage across it when it is squeezed, stretched, sheared, etc. They can be used as […]

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Bessel functions

I vaguely remember the following conversation from back when I was a PhD student. Student A: What’s a Bessel function? Student B (waving his arms about): It’s a wavy thing – goes like this, doesn’t it? Me: Sounds vaguely familiar – I think we did it in third-year. Student A: But what IS it? Me: […]

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