For the hallway picture, each blue line corresponds with what should be a parallel line, along edges of square tiles or the corner of the floor and the two walls.

For the dinosaur doll, each white dot connects a feature on the dinosaur to that feature’s reflection.

For the shadows, each white dot connects a corner of the object to the corner of the shadow.

I think each of these lines is meticulously chosen.

Let’s also assume the heat capacity of the hot dog is about 3000 J/kg*K

So the specific heat of water at those temperatures is 4184 J/kg K, and those food court hot dogs are probably about the same as Kirkland dinner franks, which have about 73g of water, 31 g of fat (specific heat of about 2300 J/ kg K), 16g of protein (1500 J/kg K), and 3g of sugars/carbs (1200 J/kg K), and let’s say negligible ash, so we’re left with a weighted average of about 3280 J/kg K.

That’s within 10% of your assumed value, so I think I just wasted my time trying to check your assumption, which was pretty close to my number that took a lot more work.

But fundamentally there is less energy storage in a charged sodium atom than a charged lithium atom so it seems sodium batteries must always be bigger and heavier than equivalent-capacity lithium batteries.

Well the battery chemistry will always include much more than just the loose charge carrier of Na+ or Li+ or whatever cation floating around. It’s always a suitable cathode material made from other elements, too. Lithium ion batteries in cars today have cathodes mostly of high performance lithium nickel manganese cobalt oxides (NMC) or cheaper/more stable lithium iron phosphate (LFP).

The dominant sodium ion chemistry hitting mass production now uses Prussian Blue Analogues for the cathode (made from a 3d matrix out of sodium, plus a metal like iron/manganese/nickel, plus cyanide made from carbon and nitrogen).

Plus even separately from the raw chemistry of the battery, built in mechanisms for durability or longevity or charge cycles or thermal management or safety or other material properties may change the overall weight of the battery for any particular performance characteristics.

In the end, the performance of the entire battery is what matters, and lithium’s head start in less weight per cation may one day be overcome if the overall materials involved can be lighter in some as-yet commercialized sodium ion chemistry.

California is famous for having different emission regulations. They have an exemption from the national law that they’re allowed to make stricter emissions and gas mileage regulations. None of those should prove to be a burden for anyone who wants to sell a battery EV in California, because there’s no standard that applies only in California to EVs.

Kia pulled its EV6 GT, which basically did not sell well in the US. They only manufactured that particular top tier trim level in Korea, but the other EV6 trim levels continue to be manufactured and sold in the U.S. (Wind, GT-Line). Kinda stupid that they named their top of the line the GT and the one just below that the GT-Line, but brands can be stupid with naming schemes sometime.

now both Hyundai and Kia have stopped selling EV models last year solely in the US

They’re basically one company and they stopped importing EVs. They still build and sell plenty of new EVs in the U.S., made in their plants in the state of Georgia. They’re also currently expanding capacity at their plants, in the hopes of catching more of the growing electric SUV market.

So they no longer sell the top of the line trim level of the Kia EV6, or the Hyundai Ioniq 6, but they’re still building and selling very similar models on the same platform. The Kia EV6 still exists in the lower trim levels, and the Ioniq 6N and the Ioniq 5 and 5N, and their smaller EVs (Kia Niro, Hyundai Kona) are still available, too. Both brands launched their 3-row electric SUVs in the US, too (Hyundai Ioniq 9, Kia EV9).

A lot of companies are slowing down their EV rollouts, but I wouldn’t say that Hyundai/Kia is the best example of that.

Average new car price has gone up a lot because the average new car has been purchased by rich people who demand high performance and luxury features. And rich people have been doing great the last 50 years, so the top of the market has totally run away with high prices.

If you actually dig into specific models and what they go for, you see that the most basic cars have only gone up slightly in price, but are also much higher performing (0-60 times, quarter mile times, braking distance), more efficient (better highway/city gas mileage), more reliable (more miles/years to failure), and have a lot more standard features that used to be expensive add-ons (automatic transmissions, power windows/locks, power steering), and are generally better constructed (smaller panel gaps, better sound proofing/vibrations), and much, much safer by pretty much every measure.

Today’s cars, even the cheapest ones, are much better than the cars from the 90’s, much less the cars from the 70’s (5-digit odometers because getting past 100,000 miles wasn’t necessarily expected, bodies that rusted within a decade of normal use).

So if a first generation Honda Civic in 1974 cost $3000 in 1974 dollars (inflation adjusted to $21,000 today), we should compare what that car was, compared to what a Honda Civic is today (starting at around $25,000 for the barebones model, $30,000 for a few nicer features). Compare torque/horsepower specs, actual performance at 0-60/quarter mile, gas mileage, all of that. I’m not entirely convinced that the people of 1974 were getting a better bargain on their cars than today’s new economy car buyer.

I hate that cars have gotten so big, and that the SUV is basically the American default at this point. But I don’t think that car prices have actually gone up that high in the 30 years I’ve been driving. And cars from before I was driving just…sucked.

It’s for showing off the engineering. Lots of robotics competitions focus on different things (throwing balls, kicking soccer balls, moving fast), but BattleBots is definitely the one I’d be most worried about advancing a dangerous line of killer tech.

A humanoid bipedal foot race shows off balance, speed, power efficiency, and things like that.

Exactly.

The whole reason why lithium is such a good material for cathodes in car batteries is because of its very low mass per cation. So for a Lithium Iron Phosphate battery, the the cathode material is LiFePO4, where the Lithium itself is only 4.4% of the overall mass of the cathode.

So it’s important to remember that although the lithium constitutes a small amount of the total mass of a battery, that swings both ways so that not much is actually needed to build the next battery out of recycled materials.

Your solar power storage expert is named Sun? Sounds lot like sun.

Maybe that’s why she became a solar power storage expert!

they could have bought a <$25k used EV last year and saved $4k with the EV tax rebate.

The people who were in the market for a car last year are by and large not the same people who are in the market today.

Plus let’s not forget, the actual EVs on the used market 12 months ago were different than today’s. Someone looking to buy a 3-year-old car today has to look for something originally sold in 2023, whereas 12 months ago they were looking at 2022 vehicles, with fewer models available and significantly fewer vehicles actually manufactured and sold.

For everything the Trump administration has done to make solar and wind power less economically feasible, it turns out his war in Iran has done way more to make fossil fuel consumption less economically feasible as well.

There really was a huge increase in the number of EV models available between model years 2018 and 2023.

So now, when you’re looking to buy a 3-year-old car, you have so many more EV options to choose from even compared to just 2 years ago.

You can choose different form factors (small cars, sedans, wagon/crossover/small SUVs, medium SUVs, literal pickup trucks), and basically any price tier from economy to ultra luxury high end.

Not every ecological niche was filled in the past 5 years, and some still need a bit more competition, but even with some pullback over the last year there are still plenty of new EVs hitting new categories (e.g., true three-row SUVs and minivans) that will feed into tomorrow’s used market.

And not every model will survive. The future of all-electric full size pickups looks pretty grim. Some entire companies might not survive the EV transition (looking at you, Honda). But overall, the used market will fill out with what was hitting the new market 5-10 years ago, and we’ll start to see a lot of consumer preferences start showing what the future of cars will look like.

goshery store

Kinda depends on the rock, right?

Starship has charged $90m so far. That’s including a healthy profit I’m sure.

SpaceX has a contract with Voyager Technologies for a 2029 launch at $90m. I would read that in the opposite direction as you, where you assume that it’s costing SpaceX less than what they’re charging. That’s far enough away that I’m not sure they’re going to be able to keep that price or be certain that they can actually launch on time or make a profit at that price.