Saturday Science: What is it all about ?

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“The lessons of science should be experimental also. The sight of a planet through a telescope is worth a whole course on astronomy; the shock of the electric spark in the elbow out-values all theories;.” – Ralph Waldo Emerson

Thanks for joining us here ! When we learn physics, we spend most of our time reading, analysing with maths and with diagrams, and this of course leads to great insight. But practical science projects should be a substantial part of learning: they make science more vivid and memorable, and lead to deep learning, especially in physics. So this website is about actually doing stuff, ‘getting your hands dirty’ with practical science and engineering projects.

Take a look at any real thing, a really close look, and you uncover another layer below the surface, then another layer beneath that – more science and more physics in each layer. Take a vehicle, like a train. It rolls along a track, it can’t be that difficult, after all its not rocket science. But not so fast ! How does the train roll ? Why doesn’t it skid ? Friction maybe ? Why doesn’t the track wear out ? What about axles ? Plain bearings & ball bearings. How do those work ? Corners, when the outer wheels have to roll further than the inside ones. Why doesn’t it stop rolling because of friction ? Steam, or diesel engines. One burns fuel outside the cylinder, one inside. But not all the fuel energy becomes driving energy. Carnot engine efficiency depends upon gas getting hot and then being cooled. How cooled ?… and so on.

Learning from practical projects is ‘pull’ learning, not ‘push’ learning: you want to figure out why something worked in a surprising way, or maybe didn’t work in a surprising way ! So you look up things, you think more deeply about things. Science clubs can offer a way of getting into more practical science projects. So go to a science club – or set one up if you don’t have one !

Press on the menu button with the triple ‘ = ‘ symbol Ξ above to get the menu/ navigation. There you will find sections about science projects and experiments you can make yourself.

Before diving into the dozens of projects on this website you might like to take a look at a video or two . The first one gives some answers to the question “Why do science projects”, while the second one shows some slightly crazy ways to literally launch a book. The third one is from the launch of my last book, The Ultimate Book of Saturday Science, which we made at Isaac Newton’s old house Woolsthorpe, where you can still see where he lived, and re-try some of his experiments in optics and mechanics.

As well as science projects, experiments and demonstrations there is a section called the Half-Bakery, where there a some half-baked projects – bright ideas that are half-tried, or worked but need further innovations. You’ll also find some tips and tricks on making things, and analysing what is going on. There is even a short section on innovation: brainstorming in teams and inventing new stuff. You might also find it interesting to take a look at the ‘blog’ below, at science and gadgets that are currently being worked on. As in the Half-Bakery section, though, you will find physics that is incomplete and projects that maybe don’t quite work – but maybe you can fix that !

Latest… Check out Sonic Molecular Mass Meters

This month we had a whole bunch of Sonic Molecular Mass Meters being road-tested by students at the British Physics Olympiad ‘camp’ in St. John’s College, University of Oxford. Read all about they work – and how you can make one – on the Saturday Science Projects page.

Saturday Science Bazookas at Big Bang Fair London South 12th July

We were at the Big Bang Fair at Sutton Grammar School with a smorgasbord of Vacuum Bazookas.  We blasted projectiles at a big target, measuring their speed, measuring the pressure, and trying different projectiles to get the last metre per second out of them.  We showed off Vacuum Engines too, and one method to measure Vacuum Bazooka projectile speeds.  And students brainstormed nearly 30 more methods to measure its speed ! 

Some more Saturday Science projects will be popping up on the website too, from ingenious new rotameters to measuring the sun with a marble !

June… IoP Rugby Meeting went with a Boyle’s Law Bang !  

This month saw us setting up Light Tunnel Sensors for workshop sessions at Highgate School.  Students figured out what was going on and managed to measure the curious exponential response of the sensor as the angle increases.  And some students had a go at programming Microbit computers to convert the exponential response to linear.

We tried brainstorming, and students came up with dozens of ways of measuring the speed of a projectile from a Vacuum Bazooka: you don’t have to use a Light Gate !  And talking of projectiles, we were once again at Clifton College, Bristol, with Vacuum Bazookas.

We were at the Institute of Physics Rugby meeting for physics teachers, on the 5th of June.  We had fun with 8 demonstrations from Boyle’s Law Bangers to Vacuum Bazookas – and in case you could’nt make it, the slides from the workshop sessions are attached here.  Satsci preso rugby 2019

May… Escape Chutes, Microbits Blowing in the Wind, Curved Space & Quantum, Free 295-page E-book

There is a free ! e-book on the website – a full downloadable printable copy of the Exploding Disk Cannons book, a paperback and hardback book, 295 pages with history, analysis, projects, tips and tricks and a ton of science that you won’t find anywhere else. There is a link to download it on the Saturday Science Books page. (Do let me know if you have problems with this).

Travelling this month both by ship and by jet plane, we noticed the escape chutes available in both. The physics and engineering of escape chutes is something on which lives can depend. Not widely known about, but they are interesting – they can be both sloping at different angles, even right up to vertical. We’ve started looking at a model chute using a Microbit with its acceleration sensor, and have the first data. And we are using the Microbit and acceleration sensor for measuring wind… its incredibly simple – but not quite working ! We’ll tell you how just as soon as we have some good data.

Finally, there’s a whole new section (‘page’), Curved Space & Quantum, which goes into the maths and algebra behind Stephen Hawking’s book Briefer History of Time. It has all the weird stuff that happens when you have things that move at incredible speed, near the speed of light, when you have enormous things like black holes, and when you move to the quantum world of the very small.

April… British Physics Olympiad in China, Magic Chinese Water Paper and more… more projects this month !

Being in China, we were reminded of the ‘magic’ paper which is used by Chinese children to learn to write the complex calligraphy of the ancient tradition of Chinese writing system. And discussing physics always involves collisions, and collisions gets you to thinking about marbles. We’ve now put up some examples of the serendipitous combination of marbles and Chinese magic water paper – now in the Marbellous section, of course.

We were also busy playing around with glow-in-the-dark gadgets like phosphorescent emergency signs charge by light and those ingenious chemical Glow Sticks which glow in the dark when the glass tube inside is broken by bending them. We monitored the light coming out versus time, with both a multimeter and also ‘intelligent’ data gathering using a Microbit computer. Interestingly, the glow seems to follows a double exponential curve, not a simple single exponential curve. A Chinese student knows something about these – we’ll report back: this is all on the Optical Realities page.

March… 6 more projects this month

This month, there is another 6 projects – Waltzing Tube in 3 Minute Sat Sci, Wet Solar Cells in Optical Realities, Pneumatic Drums in Sat Sci Projects, Light Tunnels in the Microbit Sat Sci section, Air Juggling (using a hair drier) on the Appliance of Sat Sci page, and Balloon Biceps on the Subtle Sat Sci of String page. Click on those sections to see what they are all about.

As well as all this, there has been some more exploration on the February’s ‘Latest’ posting – how kitchen hand blenders can ‘suck’ a cup or small bowl up. Then it’ll go onto one of the main pages, maybe on the 3-minute Saturday Science section.

February… Kitchen Blenders also suck

Following a tip from Esther Redhouse White (thanks Esther !), Diane and I have been playing around with how hand blenders – those electric kitchen gadgets handy for making soup out of vegetables – can actually lift up cups /small bowls of water. Really ? you might think. It may be weird but it really happens. If you don’t believe us, grab a blender and just try it yourself.

But how, why does it happen ? What is the physics behind this ?

I thought that this might be down to some kind of Bernoulli effect, because Bernoulli is often causes weird surprising effects. But now I think it might be basically down to the blender working like a peculiar sort of ‘cut-away’ centrifugal pump.

A proper centrifugal pump produces a basic pressure P given by

P = ρv2 / r

where ρ is the density, v the speed of the blade tips, and r the radius. Now it turns out that if you put some numbers in, you get forces like 10N, or 1 kilogram lift force. Could this be right ?

Well Diane had a nice idea for how to prove it: she taped a length of plastic straw to the side of the blender, going down to the centre at the bottom. There are probably some other effects going on – I am not sure what – but I think that this is 80% of the explanation of how lifting blender works. Now watch the video to see how Di’s ingenious modification works.

January… bent-pipe control

I’ve been playing around with the idea of something that gets you flow control using the bending of a tube. Most of us have stopped a garden hose by bending over to 180 degrees. In fact, though, the effect is not used in flow control – crushing the tube is preferred. Flow stopping by crushing a tube is a long established technology, used, for example, in peristaltic pumps, where a roller squeezing down on a tube pushes liquid inside it along. We’ve all seen those little plastic adjustable clips, or metal clips with a little screw that adjust flow by crushing a tube: there are thousands of them in every hospital, regulating flow of drips, for example. I’ve often thought that it would be useful to know the ‘law of pipe crushing’. What formula does flow in a crushed pipe follow versus, for example, the distance between the crushing bars in a screw clip ? Its probably fairly complicated. You can see with some tubes, for example, that the free cross-section goes smoothly from circular to oval, then, often, to a kind of elongated dumb-bell shape.


Simply squeezing the tube works fine with ultra-flexible PVC tubing of relatively small diameter. But you can also get great flow control of bigger, nominally rigid pipe, leastways reasonably thin-walled slightly flexible pipe polypropylene pipe by bending it. You can monitor the control you are getting by looking at the angle of the bend. And it has the advantage of needing no equipment other than Mk I Human Hands. We’ve used this for a while now to control the flow of air to a vacuum cleaner in vacuum-based projects. But the the pipe is really difficult to bend at first, then – OOoops ! – it bends down flat and nearly shuts off the vacuum cleaner.

Above shows the ‘Dee’-shaped cross section of the pipe – clearer in the back-lit pic on the right – which forms as it is bent against the fulcrum post. The Dee narrows as the angle of bend increases, decreases the flow. The pipe is 32mm bore, 1.5mm wall thickness polypropylene. We think that we’ve uncovered ways of making this more usable which still needs some more work… more coming soon !

ri talk question

The most exciting phrase in science is not “Eureka !”  but ‘That’s funny” – Albert Einstein  Neil A Downie doing Saturday Science at the Royal Institution, London