Thorry84
@Thorry84@feddit.nl
- Comment on Solar powered personal umbrella with battery? 2 days ago:
People always severely underestimate how little power solar panels actually produce. In optimal conditions they get around 1000 watt per square meter, but are only around 20% efficient. So that means 200 watt produced at the panel. Once you convert that into something useable and transport it to where you need it, you’ll probably lose another 5 - 10%. And that’s a square meter, that’s more than you can comfortably carry. Think a flat panel of around 2 meters in length and 0.5 meters wide and lifting that above your head, pointed perfectly at the sun.
And the reality is, most solar panels even in permanent installations don’t experience perfect conditions. They don’t track the sun, so most of the time they aren’t perfectly aligned to catch all that energy. They are most likely never aligned perfectly, or if they are just a few days out of the year for like an hour a day. The sun isn’t always out, not just because you know night time, but also because of clouds and other weather or human related stuff. Lots of times there are shadows that prevent optimal workings. Dust and grime also plays a part. But another thing is temperature, solar panels are rated at around 20 degrees C. But when you put a black thing in full sun, you know it’s going to get scorching hot. This also reduces the amount of energy you can usefully extract from the sunlight as well.
The annoying thing about solar panels is they aren’t linear at all. It isn’t like when conditions are 80% from optimal, they produce 80% of the power. No, usually it’s more like 60%. And once you drop below 40% of optimal, you just produce basically zero. With a bit of effort this can be improved upon. For example I use microinverters which can regulate each panel individually, but even then it’s not great. And that’s with state of the art panels, which are very fragile, so they have a sturdy metal frame, a very tough plastic backing and a big ass layer of glass on top to protect them. If you get those more sturdy thin and light panels, you’ll be lucky if they get 15% efficiency (most likely a lot less).
So putting solar on anything that isn’t a permanent installation is usually pointless. It’s way too hard to get those ideal conditions and the panels aren’t very good to start with. If it’s moving, it’s hard to point at the sun all the time. Exception are maybe a small panel on the top of a campervan, which is probably the best case for a mobile installation and gets just a little bit of energy. But only if it doesn’t distrub the wind profile of the van, otherwise it probably costs more in gas to push it along at high speed than it ever delivers back in electricity. One of those small foldable panels can also be useful when hiking for example. You can carry it collapsed on your back and if you take a break, you can fold it out, point it at the sun and get some useful energy for a couple of hours while you get some rest. Putting it on when hiking would be pointless, as it would be bulky when folded out, usually not pointed at the sun and under cover of trees for example.
Maybe the technology will improve in the future, but for now any useful personal solar is very niche.
- Comment on Help prevent teenage agricultural addiction 3 days ago:
Buffy <3
- Comment on YSK: What are 'forever chemicals' and why do they matter? – DW – 07/15/2025 6 days ago:
One common misconception I’ve seen is people suddenly being afraid of their PTFE items they use at home. For example coated pans or PTFE cutting boards. They throw them out, because it thinks these will hurt them.
However this is not true. The long chain molecules used in the final product are perfectly safe. They get all their useful features from being big molecules and being very inert. That’s why they are used in the first place. As such these molecules can’t interact with biologics at all. You can safely eat them, they will just pass through your body. They don’t interact with anything and are too big to get incorporated into anything.
The issue with stuff like PTFE is the production. That’s where a lot of small PFAS molecules get used and after they’ve been used they can’t easily be used again. So it’s discarded as waste. But it turns out these smaller molecules can interact with biologics and not in a good way. And as they are still pretty inert, they don’t break down at all. Hence the term forever chemicals.
Back in the day Dupont studied if those smaller PFAS molecules they were discarding into the world’s water by the boatload could do any harm. They quickly found out yes, it can do a lot of harm. But to not hurt the bottom line (number must go up), they kept it a secret. This has damaged the environment in a very significant way.
When this came to light, they set out to design a new small molecule to use in the production. One that would be safe. So they did and used that, which satisfied the public for a time. However later it was proven this is a fantasy. The new molecule is just as bad as the previous one. And it turns out any variant of these kinds of molecules are just as harmful. That’s why we now collectively call this class of molecule PFAS. Dupont probably knew about this, as the properties that made them useful in the production are the same properties that make it so dangerous to biologics. However since stuff like PTFE is too important in our modern world, we kept making the stuff. Only recently have we found out how big of a problem we are creating with that.
So when you have PTFE or similar items, please keep using them. The damage for these items is already done and the end product is safe. It would be a waste to have done the damage and then not even use the end product. But when buying new stuff, be on alert. Try to find out if PFAS was used in the production of the item and try to avoid where possible. There has been talk of laws in the EU which would require the label on a product to show if PFAS was used, so people can avoid it. But we aren’t there yet.
If we were smart, we would ban it altogether. But like I said, too much of the modern world depends on these kinds of materials. So that’s probably not going to happen.
- Comment on Can somebody please explain why the world hasn't gone nuclear yet? 1 week ago:
There has to be more to the story than that, as medical tools using radiation have had terrible accidents, but are still used a lot all over the world. And for example every day there are terrible accidents with motorcycles and in some countries that’s basically the primary mode of transportation for most people.
The true story has to be a bit more complex and nuanced?
- Comment on Star Wars is an ode to the stupidest use of battle lasers 1 week ago:
I think space opera can be sci-fi or fantasy? Star Wars is definitely fantasy tho.
- Comment on I wonder if the spice girls still get along or if that "friendship never ends" thing was just a lie. 1 week ago:
Imagine being married to a honest to god actual Spice Girl (after ditching your first wife and kids) and still having the need to sexually harass your PA. There is something not right with that man.
- Comment on oops 1 week ago:
I think my face scrub still has these. But I would have to check, it might be just sand they put in there. Works great tho
- Comment on Elon Musk's AI chatbot, Grok, started calling itself 'MechaHitler' 1 week ago:
Yes sir, we finally fixed it. It now no longer denies the holocaust.
Excellent work Jenkins! We’ve finally created the perfectly balanced and fair AI!
Well there is this one little hiccup sir. It now recommends a second holocaust and calls itself MechaHitler.
- Comment on Gelatine 1 week ago:
Yes, I love those. Especially the rainbow candy is excellent!
- Comment on Gelatine 1 week ago:
It’s good to see more and more vegan candy being sold. These days I’ve even come to expect it. When it isn’t advertised on the packaging I check the ingredients and more often than not I see they are in fact vegan.
- Comment on The Cause of Grok’s Increasing Antisemitism? Apparently, Two Lines of Code (Update: One of the Lines of Code Was Removed) 1 week ago:
I think they meant people don’t know how these models work in practice. On a theoretical level they are well understood. But in practice they behave in a chaotic way (chaotic in the math sense of the word). A small change in the input can lead to wild swings in the output. So when people want to change the way the models acts by changing the system prompt, it’s basically impossible to say what change should be made to achieve the desired outcome. And often such a change doesn’t even exist, only something that’s close enough is possible. So they have to resort to trial and error, trying to tweak things like the system prompt and seeing what happens.
- Comment on Barbers HATE this one simple trick 2 weeks ago:
3 years? I’ve been bald for 20 years and I’m 300K down the hole, when does this trick kick in exactly?
- Comment on I finished my 3D Printable screw design! Excellent print ability, reliable for simple use, though the head is prone to strip... can't win them all. 2 weeks ago:
Is that the LTT Noctua screwdriver?
- Comment on I finished my 3D Printable screw design! Excellent print ability, reliable for simple use, though the head is prone to strip... can't win them all. 2 weeks ago:
Sir, you really should use your axe to drive screws. It doesn’t even work and damages the axe. Also this is a Wendy’s.
- Comment on Corporations are saving the planet! 3 weeks ago:
Really? I never heard that before. What would they care about how their caps are? I can’t see it having any impact on them at all. A lot of people got pissed about it when Coca Cola was one of the first to change the caps in line with the regulation, so if anything it hurt Coca Cola.
Also even though large corporations are almost always totally evil, it’s not impossible for them to do something good as well. Probably not for the right reasons, but still, one thing doesn’t exclude the other.
- Comment on Earned my belly today 3 weeks ago:
Isn’t the proper technical term a “spaghet”?
- Comment on how do I stop itching? 3 weeks ago:
What did the doctor say? You may have a fungal infection, where the welts and itch aren’t caused by dryness or the scratching, but by the fungus. It’s actually really common and can be extremely annoying if left untreated. Some miconazole nitrate cream can really help out with this, just a few weeks of applying twice a day and it’ll clear up.
But never take medical advice from the internet, go see a doctor and ask them what to do.
- Comment on Be honest whose actually working today and who is goofing off 3 weeks ago:
I’m only working half day today and to be fair it’s more like hardly working than working hard.
- Comment on Trump social media site brought down by Iran hackers 4 weeks ago:
Yeah these are the dicks that cried terrorism when Tesla was “attacked”
- Comment on What's up with all the moth memes? 4 weeks ago:
Return to beans!
- Comment on I have discovered chat IS cute and so are you <3 4 weeks ago:
Thanks for not giving in to the Debbie Downers. Confirmed mods are cute as well <3
- Comment on I have discovered chat IS cute and so are you <3 4 weeks ago:
Chat is in the chat room, so if you are in the chat room, then yes.
- Submitted 4 weeks ago to showerthoughts@lemmy.world | 11 comments
- Comment on "There can be.... 4 weeks ago:
To the people who understand this meme: I hope your back is a bit better today, take care not to stoop down too much.
- Comment on If you were to launch a rocketship parallel to the earth, on wheels, how big would the ramp have to be to get it into space? 4 weeks ago:
Yes
As long as the object doesn’t reach escape velocity, it’s in orbit and thus bound by the primary object. Now this orbit can by very weird and huge, but it’s still a loop. Only above escape velocity does the loop “break” and leaving the object without a guaranteed return is possible.
So in theory if an object is in orbit and the boost is sufficient, it can just leave. However even then it is subject to the gravity fields and will make an arc instead of just a straight line. So “point and shoot” is never really an option. But often in movies a small spacecraft is seen making a small maneuver and somehow being seen as lost to space. That will for certain not be the case, a small boost just gives you a different orbit, but an orbit still.
For example the movie Life (2017) comes to mind. Spoiler alert. In the end they decide to use an escape pod to launch into “deep space” with the alien. The escape pod just points up and fires the rocket for a short while and now is lost to deep space forever. This is total nonsense. The reason escape pods can work with very little fuel is they often have just enough oompf (or delta-V if you want to be technical) to put the pod into a slightly lower orbit. This lower orbit means more drag from the atmosphere which slows it down further, lowering the orbit again etc. until the thing is slowed enough it can totally re-enter and land. It isn’t like an escape pod pointed down goes to Earth and pointed up goes into outer space. The pod actually fires in the direction of the orbit, so horizontally, in order to slow it down.
Orbital mechanics get really weird really fast. For example slowing down can cause the orbit to become higher before it goes lower. And putting in energy sideways can alter the angle of the orbit just like those spinning flywheel desk toys. Playing around with orbits in Kerbal Space Program can give a better understanding and can even make the concept of delta-V very easy to understand. KSP players would be unable to watch the movie Gravity (2013) for example without screaming at the screen: “THIS IS NOT HOW ANY OF THIS WORKS”.
It’s hard to figure out, that’s why we refer to hard things as “rocket science”. It’s not just the complexity of the rocket as a machine and engineering challenge. But also figuring out stuff like orbits, taking into account the different gravity fields of objects that are of note. Doing things like gravity assists or Hohmann transfer orbit, taking into account the influence the extremely thin atmosphere has. And remembering everything moves, so shoot for where the target is going to be, not where it is now.
- Comment on If you were to launch a rocketship parallel to the earth, on wheels, how big would the ramp have to be to get it into space? 4 weeks ago:
You are very welcome! <3
- Comment on If you were to launch a rocketship parallel to the earth, on wheels, how big would the ramp have to be to get it into space? 4 weeks ago:
There is a few different concepts here in conflict, which is why the question is hard to answer.
What do we mean when we say space? Usually we mean above the Kármán line, or above 100km. At that point you are above almost all of the atmosphere, so we consider that space. The atmosphere does actually extend quite a bit above that, but at that point it’s so thin we consider it to be space.
However as we know, the Earth has a bunch of gravity from its mass. So when you get up to 100km you just fall back down. Space isn’t free of gravity, the gravity of the Earth extends basically for ever. It’s influence does get less (thanks to Newton we know by how much), but considering the Earth is thousands of km wide when we get up to 100km we are basically still on the ground as far as gravity is concerned.
So why do we see astronauts fly around? They are weightless, so there is no gravity right? This is something popular media gets wrong a whole bunch, it’s not like there is some magically line called space and beyond there you are weightless. Those astronauts are actually in orbit, that’s why they don’t experience gravity from the Earth. To understand orbits, imagine we fire a big ass cannon. The ball flies through the air in an arc and lands on the ground. How far away it lands, depends on how fast we shot the ball. The faster it went out of the cannon, the further it flies. Now imagine we shoot the ball over the horizon, so it lands so far away we can’t even see it anymore. It still lands right? Yes, but only up to a point. It turns out if you shoot the ball fast enough, the arc just continues falling beyond the horizon until it loops around the Earth. As it is falling, it doesn’t experience gravity except for the arc it follows.
Usually when we put stuff into space, we mean put it in orbit and especially something called Low Earth Orbit . That means it needs to have a speed just like the cannon ball, to keep falling indefinitely. The speed we need is depended on how large the arc we want to have, or in other words how high the orbit is above the Earth. For context, if we want to fly in orbit in space so at an altitude of 100km, we would need to go almost 28254 km/h. Imagine driving that fast on the highway, it’s crazy fast.
That’s why we use rockets, it’s not as much about going up, it’s more about going really fast. So a rocket takes off and goes vertical for the first bit, this is to get to a thinner part of the atmosphere to reduce drag. Then it does something called the pitch over maneuver, usually in the form of a gravity turn. This is to go mostly horizontal and get that speed up. At the speeds rockets are going, they get to the 100km altitude in no time. So they pitch over as to not overshoot and use all their energy to go as fast as they can horizontally and thus into orbit. Then you get into the realm of orbital mechanics, which popular media also gets wrong a whole bunch. You can’t just point you spacecraft into space, give it a boost and be flying off into the void forever. If you want to learn more I would recommend playing Kerbal Space Program, to get a feel for how orbits work.
But say we are totally done with Earth and just want to leave it all behind, go into Deep Space. How would we do that? For that we need even more speed, something called escape velocity. If we get to that speed (40270 km/h), we can leave the Earth and go wherever we want, right? No not just yet, we might have left Earth behind, but we are still in orbit around the Sun. So we are still following orbital mechanics, only the Sun is the primary body we have to account for instead of the Earth. So we can use orbital mechanics to fly around the solar system.
If we want to leave the solar system, we would need to go even faster. But the issue is there is nothing out there. To get anywhere interesting, we would need to travel close to the speed of light for years. Even our fastest spacecraft are standing still compared to the speed of light, so leaving the solar system isn’t very useful right now. But we do have the Voyager space probes which kinda sorta left the solar system and we got some interesting data from them, which is cool!
- Comment on Button fly's 4 weeks ago:
I have both kinds and I don’t really care really. I just buy the pants because I like how they look, don’t even check what kind of fly they have. I have the ones with a regular zipper and 1 button, zipper with 2 buttons, no zipper just buttons, a little hook thingy button and fly combination. There are more important aspects of pants for me, like the fit, feeling, price and how they look.
- Comment on Celebrate my cake day 4 weeks ago:
1337 comments? You gotta pump those numbers up, those are rookie numbers!
I’m on 2213 right now, also joined around 2 years ago. So I would suggest it is in fact me who is carrying this network. Just kidding, we all know it’s Stamets@lemmy.world and by a lot.
- Comment on Amazon Doubles Prime Video Ads Per Hour 5 weeks ago:
Oi Ue, it’s fooking diabolical mate. Omelander topped me wife and now more ads on the tele, diabolical.