We all love Seasick Steve, the former tramp made famous when Jools Holland got him to play his blues on the 2006 Hootenanny TV show. One of his favourite instruments is the one-string guitar, known as a “Diddley Bow“.
A great lesson in the physics of sound can be had at all ages and stages by introducing the idea that to make a sound, something has to vibrate. Starting with twanging rubber bands and rulers, investigating the effect of changing tension and length, pupils can be set a great project to do at home – build your own diddley bo! A friend did this with her primary 5/6 class quite recently. Here are some of their instruments, and the master himself:
You can find more info on how to build your own over at One String Willie’s.
I had an interesting lesson in Physics today from an experienced roof and chimney man, Jimmy Simpson. He came to my house to check out the chimney stack, to make sure it was safe for a new stove.
The idea is to check that the chinmey isn’t blocked or leaking, so smoke is sent up the chimney to see if it’s OK, but before he does that, he uses sound:
Sound placed at base of chimney stack
What next? Then, he just nips up on the roof to listen to the sound. Muffled means there’s a blockage of some kind. Too clear down the other stacks and there’s a leak. Look at him go:
Up to the roof...
... to listen for leaks
After this, he lit a smoke stick at the base of the chimney to see it went where it was supposed to go, and didn’t, where it wasn’t. For once, something to be sniffed at.
Finally, one more trip up to the roof to give the flue a brush before cleaning up and calling the job done. Jimmy says I can go ahead and get my stove fitted.
Chim-chiminy, chim-chiminy, chim-chim-cheree, Good luck will rub off when you shakes hands with me!
Today is the anniversary of the Queen’s accession to the throne and there was a 21-gun salute from Edinburgh Castle to mark the occasion. You can see part of last year’s taken by video on the castle on YouTube. I happened to be down on Princes Street today, and caught a couple of the shots on video. Physics students should be able explain why you see the smoke from the cannon before you hear the bang. If the speed of light is 300 thousand kilometres per second and the speed of sound in air is 340 metres per second, can you work out how far away I was from the cannon?
