Who hasn’t opened a can of mixed nuts and found the Brazil nuts on top and the peanuts on the bottom? We’ll open one and look, today on Engineering Works!
It’s one of those universal experiences. Mixed nuts seem to un-mix themselves between the time they were packed and the time you open the can. It’s a question that begs for an answer. Fair warning: we don’t have one.
The phenomenon probably has implications for lots of things beyond nuts that unmix themselves. It affects all kinds of mixtures, dry cereal in boxes, for instance. Especially muesli, with its mixture of different-sized grains and flakes and nuts and fruit.
Researchers have demonstrated it with all kinds of things, down to beads of different sizes. You can do it yourself with a child’s beach bucket, some sand and rocks of different sizes. You’ll notice is that if you put the sand in first, the rocks sort of float on top of it. If you put the rocks in first, the sand slides into the open spaces between the rocks. And if you shake it enough, the sand ends up on the bottom. Always.
It’s easy to see – what’s – happening. But so far, it seems nobody has figured out why. It could be important. Think of all the things we use that depend on mixtures of solid things being the same all the way through.
We’re mixed up, too, so we’ll see you next time.
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Start the discussion: We thought this was pretty silly when we started, but now we’re not so sure. So many things depend on uniform mixtures to do what they’re supposed to. Do they stay uniform?