Weird science Wednesday again.
This week, Bobby Friction was sitting in for George Lamb, so we did a little Fact or Friction quiz on slippery stuff. You can hear it here, around 1 hr 12 minutes in.
Disclaimer: I’m a bit of a friction anorak, ever since I was sat next to Australia’s leading friction engineer on a 3 hour flight from Melbourne to Townsville.
So, let’s play:
1) There is a liquid that will flow up the side of its container. Fact or friction?
That’s fact: superfluid helium-4. Check it out in this Scientific American story - there's a link to a Polish video with dodgy subtitles too.
2) Teflon is the slipperiest substance. Fact or friction?
Friction: it’s BAM – and it was invented by accident. The "ceramic alloy" is created by combining a metal alloy of boron, aluminium and magnesium (AlMgB14) with titanium boride (TiB2). It is the 3rd hardest material and more than twice as slippery as Teflon.
3) There’s a man at the Health and Safety Executive whose job is to try not to fall over. Fact or friction?
Fact. Scientists test non-slip shoes at the UK’s Health and Safety Executive by strapping a bloke to a ramp coated with glycerol – it’s like sauce or gravy, apparently, and so simulates kitchen spills. Then they tip it up until he falls off.
Interestingly, their tests show that many “non-slip” shoes are nothing of the sort – it all depends on how you test them. No one agrees which is the best test, because it depends on how you’re moving, so there’s no one obvious standard. There’s more on non-slip testing here, if you really need to know more.
4) Slippers are called slippers because they cause you to fall over Fact or friction
Friction, obviously. Slippers can save your life – falls are hugely dangerous to the elderly: breaking your hip means an operation – which is not something elderly people cope with all that well. Trials in England show the number of elderly people falling can be reduced by 60% by giving them slippers. Some NHS trusts even operate a slipper exchange. They will give out pairs of slippers in exchange for over-sized, slippery, or trodden-down pairs.
My thought for the day was about this mockingbird story. A zoology prof in Florida has shown that mockingbirds recognise people who disturb their nests.
In the experiment, one person goes up to a mockingbird nest and touches it. They do it again the next day, wearing different clothes. The third and fourth days, the bird flew at them before they got anywhere near.
On the fifth day, a different person went up and touched the nest, and the mockingbird didn’t attack them.
It seems the bird knew who was the problem – well before they did anything.
The moral is: don’t mess with the birds. They might well know where you live.
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