Speaking of diy casting above, styrofoam makes for a great modern equivalent of lost wax casting. Although that is also a messy hobby, and potentially frustrating if the casting goes wrong since you would have to make the styrofoam again.
DIY aluminum and brass casting is something popping up from time to time, and an option to consider if you want to learn new skills or play with molten metal. The equipment needed can be had for potentially less than $100 depending on what you have around, and assembled over a weekend or two. That said, working with brass is harder than aluminum, and would take some patience to get something that looks on par with random brass hardware you could get at the store or from a real foundry. So like most hobbies, it can be a time sink compared to paying someone to do it for you. Also, I've heard second hand that there are online places that will 3D print and do the lost "wax" casting for you at reasonably rates.
(Disclaimer, I hadlooked into metal casting a lot, but have not done it myself yet, having moved from a house to an apartment before getting around to trying it out.)
I spend $100-200 per liter for optical grade alcohol, and that hasn't even been assayed by a standards body. People are more used to expensive alcohols existing, not so much for peanut butter. Then again, I haven't checked the price of peanut butter in some of the hipster food markets that make Whole Foods look cheap.
A PTFE plastic (e.g. Teflon), which resist a heck of a lot of chemicals, short of something like xenon diflouride, and even then XeF2 is still sometimes shipped in PTFE containers.
The center always travels a distance that is an average of the outside edge and the inner edge, just as if you moved a bar around instead of looking at the circle's diameter, the center moves a distance that is an average of the ends.
And that the center moves the same distance is more of a coincidence in this case. You can easily make an S shaped curve, or even an ellipse, where the center will move the same distance and you won't get the circle pointing the same way.
This works because if you roll around a circle (any sized circle), the spinning circle swings around. And it turns out that the shortening of the path on the surface of the circle works out to the exact same amount that the circle is spun around.
Worked out: If the center of moving circle of radius r goes in a circular path of radius R, and length L, then the angle the center moves around the fixed circle is L/R. The length the path where the circles touch then has length L(R-r)/R. The angle the moving circle would roll on a flat surface that length is L(R-r)/Rr=L/r - L/R, but if you add to that the L/R it also swung around, you get a total angle of L/r, which does not care about the size of the fixed circle at all, and for a path length of 2pi*r you get that the circle always ends up pointing in the same direction again. But this only works for circles because it depends on the angle and the distance going around being the same.
The funny thing, is in my experience, it is the nerdy types who have a lot of experience with technology that struggle the most to predict what people want. I've lost track of the number of very computer literate friends that said things like, "Who would use Myspace when you can get free website hosting..." or "Who would use Twitter when there are better options elsewhere... " or "Why would I do that on my phone when I could just use my computer." etc.
I've heard plenty of people name specific prices and apps that would make them want something like Google Glass, as they had specific functionality and utility in mind that would apply to their lives. I've heard others complain about wanting to use various NFC based payment schemes, but being unable to because implementation was slow on the vender end. I've heard visitors from other countries complaining about lack of ability to pay things with phones, because it is a lot more common in some other places. Even without getting into the fickleness of fashion and using things to show status, there are sizable number of people who want these things, which is more relevant to businesses than those that don't want to use new options. Although at least with smart watches, I have heard very little interest in them, and so far they aren't even providing that much of what those wanted anyway, playing more of a gamble with the fashion side of things it seems.
People have said the same things about smart phones, and a bunch of other technologies and devices, both those that became popular and those that failed. The critical combination of luck and features needed to get such things rolling is difficult to foresee, but none of it requires everyone to use, just the right target audience that enables the development of broader applications and makes something look cool.
In the big picture, it is a minor issue as most people will gloss over that completely, or just see it as some small number. And I wouldn't expect most people re-posting it to pick up on that, but someone writing the original material should have known better if they were going to report on such a subject. Unless this thing was supposed to competing in the bell equivalent of the Kessel Run.
How many things have gone wrong with Kinder Surprise eggs worldwide? I've heard of a few incidents, but they involved the child eating the contents of the plastic capsule after opening it, which could happen with any small toy.
I've seen this story making the rounds, and several versions of it keep using the claim "1 nanoamp of power per ring" which is nonsensical. Amps are not a unit of power, and even when you can crudely treat it like power (e.g. you know the voltage), it isn't an amount per ring, it would be a rate that occurs over time. If the average current is ~1 nA, and the voltage is ~2 kV, it uses about 2 microwatts of power. And at two rings a second, that would be a microjoules of energy per ring.
Wind chill comes from two parts: wind helping evaporation happen faster and the moving air preventing the build up of any heat in the air around your body (i.e. loss of an insulating layer of air, and no air partially warming up). If you look at a wind chill table of values, typically by the time you reach 50 mph, increasing the wind speed any more won't make much of a difference. Once all of the air in contact with your body is at ambient temperature, moving more air past it won't cool it any faster.
So the faster you go, the less an effect of cooling, while the effect of heating grows, even without breaking the sound barrier. Someone comments here it can be noticeable at ~63% the speed of sound. It looks like they are using the stagnation temperature, which assumes a parcel of air going from zero to full speed of the object it is hitting, then it would have to undergo some squeezing and heating. Most of the air doesn't do that around an object, as most of the air gets pushed aside instead of piling up in front of an object. Except, when going faster than sound it then has trouble moving out of the way fast enough, so then the heating really takes off there. So that estimate is a crude upper bound that becomes less crude above the speed of sound. At around the speed of sound, 17 C air would could reach up to 75 C piling up in front of a person. I've seen references in the past (maybe misremembering, can't find them at the moment) that humans can survive surprisingly high air temperatures for a couple minutes at a time, as in possibly approaching 100 C, but it probably doesn't take moving air into account.
The numbers are a bit different for airplanes, because they fly at altitudes where it is much colder than at the surface and they are more aerodynamic, but the heating on supersonic planes like the Concorde and SR71 is considerable. The Concorde would expand enough from thermal expansion to create a gap behind one of the control consoles in the cockpit, big enough that pilots stuck their hat in it when the Concorde retired. The SR-71 leaks fuel on the ground, because there are gaps in panels that close up once it gets to cruising speed.
You don't even need to put something between the magnets to have some fun (keep an eye on the clock in the corner, the whole video is shorter than a second).
When they say the closest approach until 2027, they mean closest approach for a ~1km asteroid. About once a month a 10-100 m asteroid is spotted passing closer than the distance of the Moon. And in 2011, a 400 m asteroid passed just within the lunar distance too. There is a lot of stuff out there, just most of it is not that big.
(Disclaimer, I hadlooked into metal casting a lot, but have not done it myself yet, having moved from a house to an apartment before getting around to trying it out.)
And that the center moves the same distance is more of a coincidence in this case. You can easily make an S shaped curve, or even an ellipse, where the center will move the same distance and you won't get the circle pointing the same way.
This works because if you roll around a circle (any sized circle), the spinning circle swings around. And it turns out that the shortening of the path on the surface of the circle works out to the exact same amount that the circle is spun around.
Worked out: If the center of moving circle of radius r goes in a circular path of radius R, and length L, then the angle the center moves around the fixed circle is L/R. The length the path where the circles touch then has length L(R-r)/R. The angle the moving circle would roll on a flat surface that length is L(R-r)/Rr=L/r - L/R, but if you add to that the L/R it also swung around, you get a total angle of L/r, which does not care about the size of the fixed circle at all, and for a path length of 2pi*r you get that the circle always ends up pointing in the same direction again. But this only works for circles because it depends on the angle and the distance going around being the same.
I've heard plenty of people name specific prices and apps that would make them want something like Google Glass, as they had specific functionality and utility in mind that would apply to their lives. I've heard others complain about wanting to use various NFC based payment schemes, but being unable to because implementation was slow on the vender end. I've heard visitors from other countries complaining about lack of ability to pay things with phones, because it is a lot more common in some other places. Even without getting into the fickleness of fashion and using things to show status, there are sizable number of people who want these things, which is more relevant to businesses than those that don't want to use new options. Although at least with smart watches, I have heard very little interest in them, and so far they aren't even providing that much of what those wanted anyway, playing more of a gamble with the fashion side of things it seems.
So the faster you go, the less an effect of cooling, while the effect of heating grows, even without breaking the sound barrier. Someone comments here it can be noticeable at ~63% the speed of sound. It looks like they are using the stagnation temperature, which assumes a parcel of air going from zero to full speed of the object it is hitting, then it would have to undergo some squeezing and heating. Most of the air doesn't do that around an object, as most of the air gets pushed aside instead of piling up in front of an object. Except, when going faster than sound it then has trouble moving out of the way fast enough, so then the heating really takes off there. So that estimate is a crude upper bound that becomes less crude above the speed of sound. At around the speed of sound, 17 C air would could reach up to 75 C piling up in front of a person. I've seen references in the past (maybe misremembering, can't find them at the moment) that humans can survive surprisingly high air temperatures for a couple minutes at a time, as in possibly approaching 100 C, but it probably doesn't take moving air into account.
The numbers are a bit different for airplanes, because they fly at altitudes where it is much colder than at the surface and they are more aerodynamic, but the heating on supersonic planes like the Concorde and SR71 is considerable. The Concorde would expand enough from thermal expansion to create a gap behind one of the control consoles in the cockpit, big enough that pilots stuck their hat in it when the Concorde retired. The SR-71 leaks fuel on the ground, because there are gaps in panels that close up once it gets to cruising speed.