Simple accelerometer and circular motion

I’ve just started teaching circular motion to my Year 12s. There are some obvious demonstrations you can do when teaching this topic, such as spinning a bucket of water around your head, but I’m somewhat ashamed to admit that I’ve only just discovered the floating cork accelerometer which can be used to illustrate a key idea for this topic. Watch the video to see what I mean.

Massive thank you to my colleague Ronan McDonald for making the big accelerometer and volunteering to get dizzy.

[Edit 18/6/2013 – this post inspired a lively discussion at the Institute of Physics PTNC mailing list for physics teachers, which is a hidden gem of a community and a list every teacher of physics should at least be aware of. Sign up via the web interface. Thanks to everyone who cross-posted their comments here.

Joe Rowling had a nice blog post a few days before this, too – well worth a look if circular motion is your thing.


Maker Faire UK

One reason for this site’s very existence is to try to connect the worlds of teaching and science communication. They have different needs and objectives, and they’ll use demos in different ways, but they’ll be the same demos.

So, teachers – here’s something from the world beyond the school lab, Maker Faire UK:

Maker Faire is very much its own brand of lunacy, but it captures something that for a specific type of geek is spectacularly good for the soul. And it turns out that type of geek is everywhere, in every field. The range of disciplines and the way they weave together (sometimes literally) is staggering. This year’s was the biggest UK Faire yet, with 10,000 visitors over the weekend.

I’m a huge fan of Maker Faire, and the softly-spoken, quietly-enthusiastic Dale Dougherty is a wonderful host.

“Blowing stuff up” in chemistry

The i-Biology blog writes a terrific response and meditation on the film in our previous post, and also includes this wonderful rant about chemistry demonstrations:

I think chemists have it tough when it comes to demos. Tougher than physicists, but in an odd way tougher than biologists too. Sure, there are precious few well-known biology demos (a subject for future posts, I’m sure), but chemistry is… hmm.

Look, I did a year of degree-level chemistry. I loved IR spectrometers. The only proper research paper to which I contributed was in computational chemistry. But I never really “got” chemistry. I never found that the practical work I did gave me confidence in the models I’d been taught, in part because of the bizarre ‘atomic model of the week’ strategy of late-80s A-levels. You know, the one where you’d just got comfortable with one particular version of How The World Works, only to have it pulled out from under your feet and replaced with something even more implausible. I found my eventual introduction to quantum mechanics a blessed relief, but then I’m weird.

My point is: I love chemistry demonstrations as theatre, but I’m squarely in the camp of not being able to remember any of the chemistry involved. What I think of as a ‘good’ physics demo reinforces or challenges my understanding of the principle behind it, but I rarely find the same sense of satisfaction in chemistry demos.

Is that because I’m a physicist; because chemistry demos are often used inappropriately; or because chemistry is somehow different?

Answers on the back of a £50 note to the usual address. Oh, and do check out the post at iBiology.

Are your practical lessons effective?

Alom and I made this film for the Nuffield Foundation’s new Practical Work for Learning website, which they’ve recently launched and are building up into a sizeable resource. The film tries to point up some of the pitfalls of practical work in the classroom context, and suggest approaches for improvement.

My problem with the film – and I write this as its director – is that I think it’s dull. Which I believe reduces its effectiveness, ironically. So it’s something of a relief to read comments like this:

Watching this video has definitely made me think and reflect on my own practice and I am looking forward to exploring the readings and resources on the Nuffield Foundation website

…from teacher Nicole Hinton’s blog.

Alom and I come at practical work from opposite directions, almost at opposite ends of the ‘exciting’/’educational’ spectrum. One of the things we hope to hash out on is why we agree on so much – including, for example, how ludicrous it is to present ‘exciting’ and ‘educational’ as somehow mutually exclusive.

Ben Craven’s arch demo

Science communication legend Ben Craven was in London over the weekend, giving me the chance to grab a quick bite with him while he waited for his train at King’s Cross. It also gave him time to show me a surprising demo related to his love of arches and for me to try out filming on my new iPhone 5. The picture quality is way better than my crappy old iPhone 3GS but the sound is problematic for doing something like this. Might need to invest in a lavalier mic of some sort…

[Oh, I see: requisitioning equipment via the blog. That’s your game, is it? Tsk. – Ed.]

Flames and Shadows

This is a lovely demo shown to me by Andreas Tober, the Physics technician at Alleyn’s School in Dulwich, London (which also happens to be the secondary school I attended. I left shortly before Andreas started, but we’ve somehow managed to become friends anyway. Gotta love the internet). I think this is a lovely, simple way to introduce the idea of absorption spectra. I will definitely be using it in my physics teaching next year.

How not to do the methane bubbles demo

Funnily enough, only today Paul and I were discussing the importance of jeopardy in demos, and how the ‘best’ moments (particularly for children’s audiences) are often when things ‘go wrong.’ This isn’t quite what we had in mind.

What I don’t understand is why the bubbles are being lit on the ceiling. Typically, the methane bubble demo is done with a volunteer’s hands well wetted with the soap solution, and the bubbles lit on their hands. The perceived jeopardy is very much to the volunteer. It’s a lovely routine for building trust and establishing the purpose of exploring science (you get to do things to the world that are worth doing, and nobody dies). Setting up the demo in the way shown here is, I think, less impressive and less useful.

Still, at least the fire suppression works.


Imploding Can

The imploding can demo is an old classic, often done with an old square-sided oil tin though I’m personally rather partial to the Coke can version. This, however, is something else. Commentary around the web suggests the method used here is to steam-clean the tank then seal the valves while it’s still full of steam. Which sounds plausible, and it’s not ridiculous to suspect this has been done as part of an industrial safety course.

Years ago I remember talking to David Jones about trying this – he’d long fancied having a go with a petrol tanker lorry. Even for TV the costs had looked prohibitive, and I never did find him an end-of-life tanker to play with. There’s also the minor issue of disposal to consider. But at least we can now be reasonably confident we could have made it work.

One concern, though: I’m not 100% convinced by the video. It’s from an interlaced source so it’s hard to tell for sure, but frame-by-framing the implosion makes it look to me like it’s been sped up somewhat. That said, the movement of the bogies looks appropriate. Ah, YouTube, you do so tease us with your ripped-off sources and your dodgy recompression.

Pendulums [6] – Coriolis Effect

Enough of the deep-and-meaningful musings, I’m going to wrap up Pendulum Week with perhaps my favourite pendulum demo of all time. “Foucault’s!“, I hear you cry?

Well, firstly: no need to be rude. Second: actually, no. Well, sort-of no. Which is to say, yes. Ish. Only without the… er… pendulum. Look, here it is:

…and I’ll let you, dear reader, work out what to do with this one. Lovely demo.