On Christmas Eve, child number 1 spotted a crack in a window. It’s a double-glazed window, and inspection showed that the small, horizontal crack was in the outermost pane. It was perpendicular to the frame, about three-quarters of the way up one side. The origins are a mystery. It MIGHT have something to do with […]
Continue readingTag: oscillation
Delays in feedback: Learning to drive, brain waves and COVID-19
With the numbers of new COVID-19 cases in China diminishing by the day, China now faces a problem. How to get the country back to work, or partly back to work, or more back to work, without taking too many risks with the virus taking off again. The risk can’t be eliminated, except by shutting […]
Continue readingPhysicsstop 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 […]
Continue readingModes 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 […]
Continue readingManaging 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 […]
Continue readingSeeing 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 […]
Continue readingDelayed feedback, oscillations and the police
This story from Yahoo is hilarious – about a policeman who chased himself for 20 minutes. In a nutshell, a CCTV operator sees a man acting suspiciously, unaware that it is in fact a plain clothes policeman. He radios through to the police, who pass the message on to their nearest policeman to the scene, who is, of […]
Continue readingNeurons 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 […]
Continue readingFriction: 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 […]
Continue readingSchlieren 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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