Posts by BenWilson
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Capture: Upside Down, Inside Out, in reply to Michael Bodle,
The result looks, ironically, like the Sky Tower.
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Hard News: Kitchen Hacks, in reply to Nora Leggs,
Choice. Instantly I learned something - I was trying to think how biology would be particularly relevant. Of course! Bacteria! There's the link immediately to the differential equations! Population growth models vs cooling models. When will it reach a temperature such that it's safe to put in the fridge? Considering that the main reason not to put hot things in the fridge is not because of damage to the food itself, but because you raise the temperature in the fridge and reduce it's ability to inhibit bacterial growth in the other food in there.
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Hard News: Kitchen Hacks, in reply to Gareth,
Obviously there’s a gap in the market for a kitchen physics blog…
As a subbranch of kitchen science, it's probably the lesser science. Chemistry would be the more important part of it. I wish I knew more.
I'll probably not be talking the physics any more, exam was yesterday. From now, it's going to be all about the differential equations at work in the kitchen. The only one I've studied that's relevant is about the laws of cooling, which is only a 2 dimensional problem, not interesting. If anyone can think of a phenomenon in the kitchen that's a function of 3 variables, preferably with time being one of them, let me know. I'll give you phase diagram you can work out all sorts of irrelevant shit from. It'll be a modern art masterpiece (by which I mean ugly).
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The experiment was to answer “which way boils off the water faster for the same power setting – lid on or off?”. The result was that in the small sample, it made no difference. Which contradicts the folk wisdom that it comes off faster with the lid off because the rising steam is unimpeded and no condensing water is dripping back in.
I could see arguments both ways, so figured an experiment would tell me if the difference was significant either way. My own punt was on there being no difference, despite the folk wisdom. Good to see you have an argument to support that, it was pretty much the same as my thinking.
I think we already settled that the lid on uses a lot less power to maintain a temperature, so long as that is all you want to do. I said that from the start.
But if you want to gently reduce the stuff in the pot, then leave the lid off.
Yes, you can get a lower temperature in the pot with the lid off. For maximum gentleness, don’t even turn the stove on. The water will eventually evaporate out. If you want it to render off faster, there’s no difference in time, but the lid on might save you a lot of mess. Would it mean more or less stirring needed? Hmmm. Will have to think about that. Gut feeling is that the natural convection in the pot with the lid on will be greater, so less stirring would be needed. I can see this clearly through the lid, the boiling water with the lid on is bubbling much harder than with it off, spread out much more around the pot too, rather than concentrated on the hot parts of the element.
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Legal Beagle: MPs' Pay, in reply to Graeme Edgeler,
To not sit at home on the xbox expecting others to work to put a roof over your head and earn the money to educate your children and pay your doctor’s bills?
That's an old favorite, for sure.
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Legal Beagle: MPs' Pay, in reply to Brent Jackson,
This won’t work. The median income (by definition) is the middle value. Any movement in the bottom values (eg minimum wage earners and unemployed) will make no difference unless they go past the middle value. For example, if all the unemployed got jobs that earned less than the median income, there would be no change in the median income.
That's true enough. But it would be hard to imagine that all the unemployed getting jobs wouldn't put upwards pressure on the median. It's an improvement on a mean, anyway, in which super high incomes at one end drag up the whole. Even better would be a measure of deviation from some ideal curve, although what that curve is, I don't know. My ideal curve is a flat line, but I'd say most people don't see it that way - they'd say that some difference between rich and poor should still exist as an incentive for ... um....something.
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Second effort. 403g came off from both methods in exactly 15mins. The results were exactly equal, to the gram. Gotta get back to study now, but I think that the obvious answer is looking a whole lot less obvious to me. Most curious.
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Hard News: Kitchen Hacks, in reply to Thrash Cardiom,
That's certainly the obvious answer. But I decided to put it to the test. I boiled two lots of water just now for 10 minutes one with the lid, one without, weighed them before and after. With the lid off, 267grams of water boiled off. With the lid on 261 grams came off. Considering the accuracy of my weighing apparatus, that's barely significant. Repeating again with a larger quantity and a longer time. These were in the same pot on the same element with the same setting, and I had water boiling in them beforehand (which I threw out quickly) to fix the temperature of the pot around 100C, and carefully measured the temperature of the water I was putting in, 85C each time.
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Hard News: Kitchen Hacks, in reply to linger,
Yup, if the pot is full of oil then it goes to the boiling point of oil, which is much higher.
But yeah, I agree with your underlying point: for boiling, you should only use the minimum energy input needed to maintain boiling temperature.
Unless the purpose is the vaporization of the substance. If you want to thicken a sauce, then you might as well crank it up, get it to the right thickness rapidly. Indeed that could be more power efficient, since there’s less wasted energy radiating out of the sides of the pot, just by the time being shorter. Got to stir to avoid burning, though, as the natural convection drops as it thickens, so it needs to be forced. And turning it up will make a huge difference to the time taken. 20 times as much power means the same energy through the pot in 1/20th the time.
Not sure if thickening happens faster with lid on or off (for the same power setting on the stove). Does anyone know? Gut feeling is that it would not make much difference. The steam is going to get out of the pot either way.
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Hard News: A plea for sanity on the…, in reply to DexterX,
The way Auckland is heading is to turn the inner city character suburbs into Soviet Style Sausage Apartment Blocks crammed together in mounds of leaky concrete and monocladded ghettos – there is not much that is done right..
It's got a fair way to go before it looks anything like that. Currently there's dozens of square kilometers ringing the city within a few km, of detached wooden houses. Much like the next 15 kilometers out. We're nowhere near some kind of horrible concrete jungle. Apartment blocks are few and far between.
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