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This is a question Home Science

Have you split the atom in your kitchen? Made your own fireworks? Fired a bacon rocket through your window?
We love home science experiments - tell us about your best, preferably with instructions.

Extra points for lost eyebrows / nasal hair / limbs

(, Thu 9 Aug 2012, 17:25)
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Kitchen Science Experiments are part of my job*
And one of my favourites is being able to crush a can with steam. It's easy, fairly safe and good to do at bbqs.

You will need:

Empty drinks can (without a widget)
A source of heat (gas/electric hob, BBQ, fire)
1 bowl of cold water
Something to pick the can up with - BBQ tongs or similar work well

What to do:

Take the empty beer/soft drink can, pour in a double shot of water (you shouldn't need more than that) and place it on your heat source. After a few minutes you should hear thew water inside boiling vigorously.

Now, grab your bowl of cold water (you don't need to bother with ice, cold tap water is fine) and put it close to the now very hot can.

Using your tongs (not your toungues, unless you're into that sort of thing) pick up the hot can and rapidly turn it upside down and plunge into the cold water.

The can will instantly be crushed, usually with a very satisfying sound.

Here's the science bit:
When you're heating the can, the water is boiling off into steam. This fills the can, displacing the air that was inside. When you then cool the can, the steam rapidly condenses back into water. This takes up less volume, creating a vacuum in the can. The air pressure around the can is therefore much higher than the pressure inside, and makes light work of the flimsy aluminium structure.

* - No really, they are. Have a look here for more.

Spammy plug: I'll be doing some home science demos on BBC Radio 5Live on Sunday 19th August, 7-10pm, in case you're interested in that sort of thing.

(, Wed 15 Aug 2012, 13:22, 24 replies)
great web site.
(, Wed 15 Aug 2012, 14:11, closed)
We're looking to redesign it soon. There's so much content on there now that the navigation system is just groaning under the weight.
(, Wed 15 Aug 2012, 15:43, closed)
The site looks fun and I missed the wine bottle trick the first time around so I'll have to give that a go later on (not an excuse to drink wine at all, honest).
(, Wed 15 Aug 2012, 15:14, closed)
It seems to fill the wine with lots of little bubbles...
...so may alter the flavour of the wine - we haven't done enough experiments (blind taste tests & whatnot) to confirm/refute this hypothesis.
(, Wed 15 Aug 2012, 15:28, closed)
It'll be non-permanent
if you let the bubbles settle out (it'll take ages if they are tiny) then it should be fine. Unless the wine was very, very slightly fizzy, and then you're affecting the carbonic acid in solution/CO2 in bubbles balance, which will change the flavour.

With your wine bottle trick - have you tried the "water hammer" trick on an open bottle? Oh, my, that's a fuckton of fun. Especially explaining how it works afterwards.
(, Wed 15 Aug 2012, 17:22, closed)
I have, but it's not one we're keen to put on the website/podcast/radio show...
...just in case people try it at home.
(, Wed 15 Aug 2012, 17:27, closed)
Oh go on.
what's the worst that can happen? ;)
(, Wed 15 Aug 2012, 17:29, closed)
Back to the wine though...
...I was worried the bubbles would oxidise the wine - the massive surface area of so many tiny bubbles gives plenty of diffusion surface.

Probably more a problem with reds though...
(, Wed 15 Aug 2012, 17:33, closed)
Oxidation probably shouldn't happen that fast.
But you might have point. Although it's good for reds, you might have come up with a high speed alternative to decanting...
(, Wed 15 Aug 2012, 17:35, closed)
I picked the wrong bottle I think.
I don't see the aeration being a problem since it's the gasses in the bottle being absorbed and the majority of wines need to be left a half hour or so after opening.
When I can find a bottle with a cork-type stopper that doesn't have a bent neck I'll try again.
(, Thu 16 Aug 2012, 3:43, closed)

website bookmarked, fucking brilliant. thanks.
(, Wed 15 Aug 2012, 15:40, closed)
Aw, Cheers!
Hopefully there's enough in there to keep you busy.
(, Wed 15 Aug 2012, 15:42, closed)
If I'm not mistaken
this is more or less the same priciple that George Stephenson used to make it possible to shrink a steam engine to portable size.

Or was it James Watt? Anyway, whoever it was realised that you could get a double hit from a puff of steam - once when it expanded to push a piston, and again by cooling/condensing, making it suck the piston back the other way.
(, Wed 15 Aug 2012, 16:25, closed)
You are not mistaken!
I can never remember who did what when it comes to steam engines...
(, Wed 15 Aug 2012, 16:34, closed)
And I agree
that is a really good website.

me and the kids are going to destroy some stuff this weekend.
(, Wed 15 Aug 2012, 16:54, closed)
Have fun!
If you want messy, but not particularly destructive demos, you could have a volcanic afternoon:

Flour Volcano - demonstrates how volcanoes form a caldera

Wallpaper Paste Volcano - a great eruption that demonstrates the effect of dissolved gases in volcanoes.
(, Wed 15 Aug 2012, 17:04, closed)
or the old school dilantant fluid behaviour
with cornflour and water can keep small children entertained for hours.
(, Wed 15 Aug 2012, 17:20, closed)
Not seen that one before
presumably the water can't rush into the can fast enough to equalise the reducing pressure from the condensing steam?

I do a lot of this kind of stuff at science festivals as well (google EPSRC Noisemakers), some of your experiments are excellent (if sadly incompatible with the level of health and safety required for, say, cheltenham science fesival. I nearly got banned from there after a hymen piston experiment went awry)
(, Wed 15 Aug 2012, 17:18, closed)
Ah, you're one of the Noisemakers?
We've got some EPSRC funding, so regularly get noisemakers involved. Come to the Cambridge Science Festival - they're happy for you to do pretty much anything as long as it's risk assessed properly...
(, Wed 15 Aug 2012, 17:26, closed)
The NOISE programme's been pulled, sadly (or at least has no more money)
we only tend to do stuff of our own backs now, so I only tend to do stuff in Scotland for the last year or so.
(, Wed 15 Aug 2012, 17:29, closed)
Will you be at the British Science Festival in Aberdeen?
We do science news for BBC Scotland, so will be up there all week...

(I did wonder why the publicity chap for NOISEmakers had stopped calling...)
(, Wed 15 Aug 2012, 17:30, closed)
Not personally.
I was at Edinburgh Science Festival and then I was a judge for Big Bang Scotland so I can't really spare any more time this year, my research groups are getting a little twitchy...

There will be someone from my lot there for sure, though. Just not sure who.
(, Wed 15 Aug 2012, 17:34, closed)
I showed
my kids how to do that about 10-11 years ago. It's bloody good.
(, Wed 15 Aug 2012, 20:50, closed)
Like this. I agree, it IS awesome.

Press 8 to jump to the punchline, or watch the whole 2 minutes to hear me teaching my class...
(, Thu 16 Aug 2012, 0:14, closed)

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