tunetardis

joined 1 year ago
[–] [email protected] 6 points 8 months ago (6 children)

Jamaican patties. You can pick up a big box of them frozen from almost anywhere (at least where I live) and heat them up in one minute. I mentioned to a Gen Z in the fall that this got me through many a college all-nighter and noticed when I was at their place last weekend, they were all stocked up! Feels good to pass on the torch…

[–] [email protected] 1 points 9 months ago* (last edited 9 months ago)

100g * 9.832m²/s

That should be 100g * 9.832m/s², or better yet 0.1kg * 9.832m/s² to get a number in newtons (N).

From a high school physics perspective, holding a 100g object steady for any length of time does no work, since work is force applied over a distance, measured in joules (J). What you do have is gravitational potential energy. Potential energy is the ability to do work, also measured in joules. Once you release the object, then you actually start getting numbers for work and power.

Power, measured in watts (W), is work done per unit time. So 10W/hr would be (10J/s)/hr. I guess that would be the rate of change of power consumption, if that were useful to you?

In theory, energy and work should be measured in joules. Simple as that. But this unit of kwh (kilowatt∙hour) has come into vogue, presumably because that's what power utilities show on the meter outside your house? 1 kW∙hr = 1 kJ/s∙hr ∙ (1000J / kJ) * (3600s / hr) = 3.6MJ. So now we're back from power to energy consumption.

[–] [email protected] 1 points 9 months ago

At least it appears to be available in Canada now…

[–] [email protected] 16 points 9 months ago (3 children)

I signed up and so far my feed seems to be dominated by a lot of bird pics. I guess that's fitting for a site called bluesky?

[–] [email protected] 7 points 9 months ago (1 children)

My fave has gotta be kwh/yr/ft². I came across that while researching the lighting requirements for hydroponics.

[–] [email protected] 3 points 9 months ago

Noted. Thanks!

[–] [email protected] 24 points 9 months ago (8 children)

#2 is certainly food for thought. So the idea is that from a journalistic fact-checking point of view, it is more important to convey the information exactly as it was presented than to verify its accuracy?

This would explain why science/engineering-based articles are so commonly inaccurate or missing in critical details. The journalist can fall back on saying "I have a recording of an interview with the expert after we downed a few pints at the pub, and I'm just parroting back what he said. Don't shoot the messenger!"

[–] [email protected] 137 points 9 months ago (37 children)

holds the potential to store up to 2 MW of energy

2nd paragraph and he's already lost me. It would be nice if tech columnists had the equivalent of even a single semester of high school physics.

[–] [email protected] 6 points 10 months ago

I treat self-checkout as a game with 2 goals:

  1. Make it through the process without getting any help.
  2. Do it as fast as a trained cashier.

In a good season, my batting average for #1 might be .300, which would not be bad were the game baseball. As far as #2 is concerned, I have never come close. It's like I throw 30 mph pitches. Things get real when I'm trying to look up bananas or something and the helper comes up behind me. "It's 4198. Here, let me do it." Thanks, I already lost #2 and you just made me lose #1…again.

[–] [email protected] 1 points 10 months ago

Oh you're right, the Zhuque-2 apparently launched successfully in July, 2023. (There had been an earlier launch in '22 but it ran into trouble.)

[–] [email protected] 2 points 10 months ago

Ok, so we're onto capacitors and fuel cells now. Here we go with my mental image of those.

On the pros side, capacitors can charge/discharge in an instant, have nearly perfect energy recovery (almost everything you put in comes back out), and have almost limitless charging cycles with no memory effects or any of that nonsense. On the cons side, even a supercapacitor can't match battery tech for energy storage density and they tend to be not so great for long-term electrical storage.

Fuel cells are sort of the opposite. Once you've sorted out the challenges in producing/storing/transporting hydrogen (these are all non-trivial but not necessarily deal-breakers either?), you're looking at essentially limitless storage duration since it's, well, a fuel. Like you can stockpile it for next year. The energy density is enviably high, though with pure hydrogen, you're doing better by weight than by volume. In any case though, it's looking pretty good compared to batteries.

But pulling the energy out of them in a timely manner is a major pain. You need either a chemical or thermal catalyst to speed it along for most applications. And the chemical of choice is platinum, which is not exactly abundant. If you wanted a fuel cell in every car, is there even enough on Earth for that? I'm not so sure.

Also, I have read impurities in the fuel can really mess up this type of fuel cell. The thermal type is purportedly more forgiving in this respect, though I picture thermal fuel cells as these hulking things that would work best as stationary power plants? Well, maybe they would be a good fit for large ships? It's hard to picture some giant container vessel plying the oceans on battery power, at any rate.

view more: ‹ prev next ›