Children are up to five times more likely to get lead in their bodies, so under no circumstances should children get leaded tin in their hands.
It is possible to get lead poisoning through the skin even as an adult if lead is handled daily. Fortunately, nowadays lead-free tin is used, but I know that some hobbyists still have a lot of lead in their stores.
Occupational exposure is a lot different than home exposure. People soldering on the job are doing so for hours a day, every day. You soldering as a hobby are not.
The dose makes the poison.
Of course, nothing is completely without risk, and an argument can be made that avoiding any avoidable risk is good, even if that risk is tiny. But the risk that comes from the fumes of soldering, unless you're doing it a whole lot, are much, much smaller than lots of risks you take every day without worry.
Everyone has a different risk tolerance. For instance, I intentionally use leaded solder because it works so much better than the lead-free varieties. But I'm cautious to avoid handling the stuff if I have any open wounds on my hands, and to avoid touching my face until I've washed my hands. That's an acceptable risk for me.
If I see correctly, the base of the screen is screwed to the hull? At least there is now less than the advertised 12.7 cm of carbon fibre composite at that point.
I had a similar thought. When I saw the monitors, I thought "How are they mounted to the hull? They wouldn't screw them into it...." well, it turns out they did.
Which is a bad idea in any sense. But then, looking at the pictures, I wouldn't dive deeper than a bathtub in that thing, even if I was paid 250k to do so. It looks like a carbon fiber tube with some clued on cameras, lights, propulsion and balast. Which is far, far from being a properly designed and engineered sub. Or boat. Or piece of furniture...
Furthermore, the energy needed for takeoff is significantly higher than the energy for cruising. For an hour's flight, it's close to 50/50. The impact is disproportionately skewed towards shorter fkights
No. It is not the takeoff as in "raising the wheels from the tarmac" part that is consuming most energy, but reaching the flight altitude. Real case, with smaller plane, I take off in 300 meters in less than 30 seconds at max power, than raise to 3000m in more than 10 minutes of 90% power. That makes the assisted takeoff less than 10% of the energy to get to cruise altitude.
I don't have the numbers for a jet fighter on a carrier, but I think it is in the same range. The takeoff assist is not for saving fuel, but to allow takeoff at the loadout of the plane that would require otherwise a longer runway or lighter loadout (less fuel and weapons).
We could, but it would require new aircraft. Passenger aircraft are not designed for that kind of stress. I'm not sure that passengers would like that much acceleration either.
I don't know that it would actually save anything though. Aircraft of carriers are held back while they throttle the engine to full throttle. Only after the pilot is convinced the engine will run long enough to take off do they release the brakes - probably using more fuel than a regular takeoff. (the other option is to get in the air and then discover the engine isn't running and so you crash land a few meters later). I'd want a real aircraft engineer to speak to this.
You could save some energy by catapulting a plane at a reasonable acceleration, like a glider is launched with a ground tractor wire. I flied gliders this way and I think the acceleration was not worse than a regular airliner. Problem is, the saving is not worth the cost and complexity.
The carrier example is wrong, the planes stay on the catapult only a few seconds while they go full throttle (this takes time), even with the burn rate it is not a significant quantity of fuel. Regular planes can do the same on the runway, I did it myself several times for fun, but it rarely bring benefits - the only place where it helps is with very short runways. In any case, the fuel consumption is not significant.
How about you elevator passengers up to a runway that is a thousand feet up in the air. Then use electric lines on the runway to power the takeoff to avoid using any onboard batteries until airborne. Just daydreaming here a bit!
It is easy, you put small BLDCs in the wheels. No need to push on air while you are on the ground. You could also have basically a super car drone or a maglev rail under the plane, launch it into the sky.
You need a big centrifuge where you can live or at least sleep and do physical exercises. It should eliminate the health problems caused by low gravity.
At the macro scale, correct. Humans might cool the outer crust somewhat in localised regions. Odds we'll be able to significantly change overall core and mantle thermodynamics are exceedingly slight.
At the micro scale, that is, for an individual geothermal well or source, not so much. Single wells or geothermal fields may be depleted or degraded.
Because heat conductivity of rock is very limited, extraction of that heat by some mechanism will eventually cool that rock below viable levels for power generation. For enhanced intensive geothermal energy --- drilling holes in rock to depths of multiple kilometers and circulating a working fluid (typically water) through the substrate --- that is thought to be on the order of 1--3 decades. After which the borehole is no longer viable and must be left to recover for some period of time, perhaps centuries.
For conventional (geyser / steam vent) geothermal, the limiting factor tends to be groundwater. The instance I'm most familiar with is The Geysers powerplant in northern California, which saw a roughly 40% reduction in capacity over several decades as the groundwater feeding the geyser system was depleted. That would have to be restored by some means.
Note too that there may be contamination issues in repeatedly cycling deep-layer water to the surface, particularly of heavy metals or radioactive isotopes. These include "sulfur, vanadium, silica compounds, chlorides, arsenic, mercury, nickel, and other heavy metals".
Source: https://www.hse.gov.uk/lung-disease/electronics-soldering.ht...
Children are up to five times more likely to get lead in their bodies, so under no circumstances should children get leaded tin in their hands.
It is possible to get lead poisoning through the skin even as an adult if lead is handled daily. Fortunately, nowadays lead-free tin is used, but I know that some hobbyists still have a lot of lead in their stores.