ScienceNostalgia101

I'm a little reluctant to butt in, but I'm slightly concerned that the OP seems somewhat new to chemistry (I don't have much hands-on experience but I've done a few chem courses in college and watched a lot of chem videos) so I figured just in case OP plans on doing this indoors I should ask whether or not rebar releases toxic fumes when dissolved in hydrochloric acid like silver does in nitric. Because if it does, it might be an idea to do this outdoors or in a fume hood.

Gah, forgot about this thread until now. Thank you for the info on salmon, Sensei. In the meantime, another question now, hopefully I'll remember to check the thread more frequently, and it is also on the topic of fluid dynamics. WARNING: Game portrays graphic violence: https://www.youtube.com/watch?v=JU9e_7QRF5A#t=1m27s In Ninja Gaiden Black, an airship is flying through a cloud during a thunderstorm. There appears to be no gap between the cloud and the windows. Assailants break open an exterior window attempting to attack the protagonist, and none of the mist from the cloud appears to wet the inside surfaces of the airship. I'll put aside whether or not it's at a high enough altitude for explosive decompression, but if, let's say, the motion of the cloud were either parallel or antiparallel to the motion of the airship (ie. no perpendicular components) would air and/or moisture be more likely to enter the airship or leave the airship? Would small enough liquid water droplets be in simple random motion analogous to the air molecules, or moving directly parallel to the outdoor airflow? Would the turbulence of the airflow ensure that some liquid water droplets made it inside if only by simple random chance?

I'm well aware that much of a teacher's time is spent marking; it is partly because of that, not in spite of that, that I proposed the one time slot, one course approach; 1/6 of the teaching burden translates to 1/6 of the marking burden, spreading it out amongst a greater fraction of the public, partly because many hands make light work and partly to prove to them just how much work is involved in the job. (How many voters say things like "teachers get paid to work 6 hours half the days of the year?") If there are many learning styles, why not give students the option of learning by video or book, rather than imposing the latter on them? Stuff that in theory is in the discretion of the individual teacher in practice might be bad for a teacher's career if popular opinion among voters who elect the school board officials doesn't favour it. I think drawing public attention to the benefits of these things will allow them to more effectively be done top-down.

Got it, thanks! The abstract looks very promising and I'll read the rest of it when I get a chance.

They're not THE most pressing concerns, but every little bit helps. A youth centre could supervise their kids too, but for some reason taxpayer support doesn't seem to be as strong for that sort of thing. Even though they'd probably do better on a science quiz after binge-watching Magic School Bus in the lounge room than in an average science classroom.

Not yet, but if it's "urgent just barely short of too late" now, it might've been simply "too late" if not for the hundreds of millions of potential polluters prevented from being born. That said, this whole notion might be re-evaluated based on the case CharonY's source has to make.

So I was recently thinking; hot air balloons, as a travel mechanism and leisure activity, use hot air for buoyancy on a large scale, and party balloons use helium on a small scale. Is there a way to form a middle ground between these traits? Not between helium and a large scale, but between hot air and a small scale. Is there any substance out of which a small-scale balloon can be made that can withstand steam (or at the very least warm, humid air) with which it is inflated and/or be well-insulated to retain its higher temperature for a non-trivial amount of its ascent through cold winter air? I ask this partly out of curiosity; partly because I'm considering trying it myself if I can carry out with proper safety precautions; and partly because I'm thinking, if this works, this will serve not only as a good demonstration of buoyancy (warmer than surroundings = ascent) but convection as well. (Once it cools, the liquid water weighs it down and it falls back to the ground.) This will also serve as a form of balloon that, even if let go into the air, could theoretically fall back down on its own before reaching an altitude at which it breaks, as opposed to a helium balloon which would just keep rising and rising. A re-usable balloon, in other words.

I would very much like that. I used to outright condone the one-child policy, (now I'm less sure what to think of it, other than considering the objections semi-hypocritical in light of the OP) but my contempt for the Chinese government has lately been growing for obvious reasons and I would love anything that could justify considering this criterion as valid a criticism of them as all the others.

So the pandemic has cast much about education in a whole new light. For all people's virtue-signaling about lofty ideals of education, it seems a lot of people were just using the education system as a de facto babysitting centre. Makes one wonder what else people have to say about it they might not really mean. While we're re-evaluating voters' reasons for supporting the education system, (or at least its continued existence) let's re-evaluate our ideas on what to do with it. 1. I think standardized testing should be lower-stakes, but more frequent. Disagreement among teachers about "how good is good" as far as student answers go, let alone which answers fit the bill compared to each other, should not be playing too crucial a role in entrance to university. A standardized test assessed exclusively by former teachers at that grade level, where each teacher assesses a different question, but assesses it for each student, should keep even the most unintended biases to a reasonable minimum. However, the present approach to high-stakes testing lends too much weight on too few tests, causing anyone who isn't at their A-game that day for a variety of legitimate reasons to have the deck stacked against them. 2. If we can't give students re-usable textbooks without getting parents' complaints about graffiti and students' complaints about how heavy their backpacks are; and we can't give students single-use worksheets without environmentalists complaining that we're wasting paper (never mind that, according to the education system's own statements about the carbon cycle, a tree being converted to paper and burned is better climate-wise than it dying and rotting in the forest) why not just print standardized re-usable elaminated worksheets, and have them show their workings in their exercise books so that they don't waste quite as much paper, and have less-heavy backpacks with less potential for graffiti? (Putting aside the risk of marking on them with sharpies, in which case, since it's only a few worksheets a week, it'd be easier to tell who was responsible than with an entire textbook?) 3. Bring coats into the classroom. Not to wear them, but to leave them on the chair in case of a fire in the middle of winter. You can't "stand by the fire" to keep warm; if you're downwind from the fire there's bound to be a distance at which you get smoke inhalation and frostbite at the same time. Have them bring in their coats. Putting them in their lockers reduces space for other items, and in practice at some middle schools some students leave their lockers unlocked anyway. 4. Speaking of which, why can't paper waste (to whatever extent it is inevitable and/or worse than the alternatives) be incinerated in the backyards of schools? I don't mean open-pit fires, but rather a closed, tightly-knit wire-mesh where all the paper waste from [x] past few weeks (however much is the right tradeoff between safety and efficiency to burn) is burned underneath a giant pot of water, whether to make enough coffee for everyone or turn a turbine, (or both, if it can be safely done) so as to demonstrate many principles of physics and chemistry, while demonstrating a good environmental alternative to throwing paper in the trash at the same time? 5. We're told students should be "involved" in the lesson, rather than just being talked to about the content. Something like mixing chemicals is something they can do for themselves while seeing the results, while changing electron energy levels... well, they can see the colours that result, but not the orbitals themselves. So why not make science cross-curricular with physical education, and have students role-play electrons in different orbitals? 6. So what's with the bias in favour of the written word? People are assessed on aspects of books that weren't in their movie adaptations, and some schools even do silent reading where it doesn't matter what you're reading, as long as it's a book. If the point of books like To Kill A Mockingbird was to tackle racism, doesn't the movie do so comparably effectively, if possibly more? If the point of books like Sarah Plain And Tall was to tackle the struggles of the old midwest, doesn't the movie do so comparably effectively, if possibly more? What business is it of the taxpayer the medium by which students choose to consume their fiction? 7. How do we tackle the topics about which the education system has cried wolf? Most famously the "marijuana is addictive" myth, but even things like claiming people used to believe the world was round, or that Edison invented the light bulb, tarnish the education system's credibility among those who know these things aren't true. How does the education system come clean about this without tarnishing its reputation even further? (Maintaining lies on the taxpayer's dime is not an acceptable option.) 8. Last but not least... why not have teaching be a secondary job instead of their only job? A teacher who teaches only one slot of one course will have plenty of time left over for a second part-time job, if not a full-time one, and students seem to have much more respect for teachers who are teaching from experience than from someone who teaches only from what other academics taught them. Even if the latter looks more like them.

Right, but perceived culpability for climate change; and whether or not the response is just; affects people's motivations to act on the issue, or they wouldn't bring it up. Even if the people bringing it up are being disingenuous, that still leaves voters they're pandering to whose willingness to act on climate change hinges on "who's pulling their weight" and who isn't, for real. So why CO2 per person isn't considered the relevant criteria; yet China preventing fewer potential future polluters from being born isn't either; is still a question worth considering.

For the record, I say this as someone who believes China needs to be called out more on its disproportionate role in foreign overfishing, in ozone depletion, etc... yet finds it odd that people deflect criticism of American greenhouse gas emissions by comparing them to total Chinese greenhouse gas emissions, instead of per-capita ones. Why is it that the total country's emissions matter more than the per capita emissions? Wouldn't it be more meaningful to compare the USA to, let's say, a randomly selected region of China containing a comparable number of people to the USA? For that matter, China's "one-child policy;" though implemented more for economic reasons than for environmental ones, is estimated to have prevented hundreds of millions of births. Why, then, are the same people who deflect criticism of American greenhouse gas emissions with references to Chinese greenhouse gas emissions therefore in turn crediting the one-child policy with cutting China's greenhouse gas emissions by double-digit percentages? If it's because they're climate change denialists, how come they aren't saying so outright? If not, why is it?

So with the rise of "E-sports," people who tout sports over video games have shifted their argument from their previous "but sports are more normal" to their current "but sports are healthier." But there's a tradeoff. Video games don't give you exercise, but they're also less likely to get you killed. As such, that leaves the question. Why have sports in particular become the go-to standard for encouraging fitness? Parents drive their kids to sports practice, which burns more fossil fuels and fewer calories than if they rode their bicycles there. But then if they rode their bicycles there, they might be too tired to give it their all when they get there. Individuals drive to the gym, which in cities might be a case of their car being cleaner than the outdoor air, but this sort of thing happens in clean-air small-towns as well. I keep hearing it's about teamwork, but aren't there other ways to encourage teamwork? Like, let's say, have students bicycle to and from school, and work as a team to figure out how to set up a tarp that will protect their bicycle paths from the rain and snow? What are the supposed benefits of sports, and the supposed alternatives to it? As nostalgic as I am for cartoons and video games, I'm thinking that can't necessarily be the most constructive way for kids to spend their spare time either. (Putting aside that one could always watch cartoons on the treadmill, lame as that may sound.)

Got it, thanks! Speaking of The Simpsons... DISCLAIMER: I would not try this at home. NOR at any convenience store, for that matter. However, it reminds me of my curiosity about the issue of cryonics. I'm not sure who to believe on this issue. There are those who claim there are ways to survive being cryogenically frozen, if society would invest in them. Others dismiss it as hopeless. Are the former just wishfully thinking? Are the latter just trying to stop cryonics from cutting in on religion's afterlife action? If I found a professional service to freeze my body, would it be safer to do it immediately after death, immediately before death, or significantly before death in the context of some terminal illness or whatever? (Obviously I'm not going to cut drastically short whatever life I have now just on the offchance of being revived later.)

If wetmarkets create new diseases by having so many different species of animals in close proximity, how come zoos aren't as prone to creating new diseases?

Question 1: Would the deliberate germ exposure lifestyle advocated by comedians like George Carlin have made people's immune systems better equipped to deal with diseases like this one? Why or why not? Question 2: Would a food-delivery equivalent of mass transit; such as, let's say, a large, moving trolley that does curbside delivery of food parcels with recipients' names on them (be it by mechanically tossing them or leaving people to walk by and pick them up) be more likely to spread disease, or less so?

Technically a TV scene and not a movie scene, but in this Simpsons scene, an avalanche buries a cabin. Homer finds out by opening the door; only for the snow that formed around the cabin to fall inward. 1. Would the snow, once it has buried the cabin, maintain its shape even if an open window or door gives it a new path downward? Or would gravity force the compressed snow to expand again into the cabin? 2. Wouldn't the snow outside look dark from the inside, because of the snow's scattering of sunlight? Is there any formula for light intensity as a function of snow depth?

Sorry to bump this again, but I have another question; what about waterwheels? If one lined every river in the USA with height-adjustable waterwheels, would that be a means to convert rivers' kinetic energy into electrical energy? Could they be mass-manufactured cheaply enough to supply the USA's energy needs if one were to put every unemployed American to work manufacturing them?

I'm not sure whether this belongs in the physics of movies thread or not, but I figure I should have a spearate thread for video games given the interactive nature of the medium. In one part of Kaizo Mario 3, Mario is temporarily in projectile motion, until his trajectory crosses paths with a waterfall. At this point, the viscosity of his surroundings is no longer negligible, and therefore, he can push his feet downward against the water to propel himself upward. I assume it's exaggerated, and that one couldn't possible propel oneself to THAT extent in real life. But at the same time, this leaves me wondering whether it's possible to "slightly" propel oneself this way, or not at all because it violates conservation of momentum. I know in horizontal motion, one can swim by pushing the water back and therefore propelling oneself forward; it's a matter of encountering less water resistance when putting your hands in front of you than when pushing the water behind you. Could the same thing work vertically? Does it depend on whether one positions oneself for it before entering the waterfall or after?

Another question now (sorry to keep bumping this, but it's not letting me edit the previous post now) but I was wondering another thing. I mentioned before the question of a concave arrangement of various small mirrors, vs. one large concave mirror, in the context of solar collectors on land. It was pointed out that in that context, it's better to have a number of small mirrors than one large one. Does the same apply to thermal solar power at sea? If one were to mass-manufacture, and then arrange into a concave pattern, a series of small mirrors, could most of the thermal energy that would otherwise fall on the Atlantic Ocean instead be captured by these solar collectors, if they were made to float in the ocean? (Presumably tied to each other and the land, to prevent them from being swept away by the currents...)

For the record I wasn't referring to using indoor appliances outdoors so much as whether or not there's some outdoor equivalent that'd still keep it cold on abnormally warm (as far as winter goes) days. In any case, I was surprised to learn they manage to store ice all year, let alone through the occasional warm day within winter. I guess anything well insulated enough with enough ice in it would prevent the temperature from going too far above freezing, if only by convection. (Though I'd be terrified of accidentally locking myself in one.)

Can't edit prior post. Have a new energy-saver inquiry. Is it more energy-efficient, in the wintertime, to have an outdoor refrigerator/freezer, such that the temperature difference between the outdoor air and refrigerator/freezer is less than that between the indoor air and refrigerator/freezer, or less efficient because an indoor refrigerator/freezer releases heat into its surroundings anyway?

I forgot to reply to this earlier. I'd like to take this opportunity to ask; should this be the same thread or a separate one? Because I can think of some things that blur the distinction between "increasing power production" and "reducing current power usage." For instance, suppose that instead of throwing paper waste away, one were to burn it for heat. There are two ways I can think of for this heat to be used: A) Put a metal tube above the fire that does not allow smoke to enter, but allows the heat energy to conduct through, so that enclosed air molecules can warm up from contact with this surface and enter any household to which this tube is connected, or... B) Just directly boil water above it and use it to cook food or brew coffee. Would either of these be more efficient; or less; than transporting everyone's paper waste to an incinerator that uses higher temperatures to generate electricity? (Efficiency of an engine; if I recall correctly, is a strictly monotonic function of difference in temperature between the hot reservoir and cold reservoir, correct?)

Depends on the temperature, I think. At higher temperatures a 1% shift in humidity counts for more than that of lower temperatures. In any case, thanks for the clarification.

Not quite, just that all that excess water vapour pumped into the air would shift the equilibrium somewhat, sort of like how a weight hanging from a spring shifts its equilibrium. Still an unreasonable assumption?

I mean the latent heat of vaporization; as in, yes, it's still around, but more of it as potential energy and less as kinetic? Sounds good, but sounds like it'd take a while to make such drastic changes to infrastructure, whereas climate change needs to be dealt with more urgently. Maybe something to think of after the climate crisis is resolved?