The quote at the end is perfect. Be excited when you are wrong because it's information.
Science Memes
Welcome to c/science_memes @ Mander.xyz!
A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.
Rules
- Don't throw mud. Behave like an intellectual and remember the human.
- Keep it rooted (on topic).
- No spam.
- Infographics welcome, get schooled.
This is a science community. We use the Dawkins definition of meme.
Research Committee
Other Mander Communities
Science and Research
Biology and Life Sciences
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- !reptiles and [email protected]
Physical Sciences
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
- [email protected]
Humanities and Social Sciences
Practical and Applied Sciences
- !exercise-and [email protected]
- [email protected]
- !self [email protected]
- [email protected]
- [email protected]
- [email protected]
Memes
Miscellaneous
It make me really sad when I learned that James and Adam were not friend.
James said their relationship doesn't really extend beyond the show.
That's fine and I think its pretty much the perfect example of a solid professional relationship (no need to be buddies or "like a family") and what greatness can be achieved when you work with same endgame in mind. They may have disagreed plenty but only because they wanted to achieve the best outcomes possible.
While they are not friends, if you follow Adam on youtube, you'll realize there is a huge amount of mutual respect between the two, even to this day.
My favorite is the fan mounted to the boat blowing the sail causing the boat to move. I mean there are a shitload more experiments in fun episodes that are far better and more entertaining, but this one is my favorite because it flies in the face of logic. It shouldn’t work. My brain rejects the possibility. But physics and fluid flow work otherwise and I found it pointlessly infuriating only because I’d been unassailable in my confidence that it couldn’t possibly work. Yet there it is with a perfectly logical explanation. I still find it irritating even if I accept the reality of it. (Episode 165 if anyone’s wondering)
That said, I still follow Adam on various platforms. That enthusiasm and joy of discovery is all still there, along with some maturity and some life observations. Literally the only celebrity figure I follow.
Love this show
My favorite is planes on a treadmill.
Mostly because fans still argue about it and it’s hit the point they had to ban PoaT comments.
Which is insane as it’s not that difficult to understand. When a plane is on the ground, its gear/wheels will roll at ground speed, but the wings provide lift at airspeed.
If the ground is being moved under the plane (as on a treadmill,) the wheels will just roll faster.
Sure they’re not zero friction and some of that needs to be overcome; but this is something encountered on a daily basis all across the world- or rather, the opposite.
If the wind is coming from ahead, its airspeed is increased and the plane needs a lower ground speed to get into the air where if the wind is coming from behind, then they need more.
(This is why carriers set course into the wind when launching jets,)
At no point is ground speed and airspeed necessarily the same (i suppose you could have a calm day, but most days, the wind is blowing at least some.)
Plane on a treadmill is really interesting because if you understand how planes work its so obvious what will happen you don't need to test it. Planes move on the ground by running their engines, which push against the air, the wheels provide zero motive force. It's also why planes need tugs to move away from the gate, you can't run the engines in reverse. Planes are not cars, but people tend to assume the thing they don't understand works like the thing they do understand, and refuse to believe their hasty assumption is wrong even when told directly their hasty assumption is wrong.
my criticism of PoaT actually has to do with the scale model they used to prove it.
scale aircraft have ridiculous power-to-weight ratios
but that's just me being a stickler.
You actually can run the engines in reverse. They have thrust reversers. There's very good reasons that they do not reverse the plane from the stand using the engines, but it is possible.
Which is insane as it’s not that difficult to understand
I found it hard to understand because neither they nor any of the other sources I've seen explaining this even attempted to answer what I thought was an incredibly obvious question: at what point does this become true? A stationary aeroplane on a treadmill will obviously move with the treadmill. I assume an aeroplane moving at like 1 km/h still gets pulled backward by the treadmill. At what point does the transition occur, and what does that transition process look like? Why can't a treadmill prevent the plane from taking off by pulling it backwards by never letting it start getting forward motion? Where does the lift come from?
I can understand how a treadmill doesn't stop a plane that's already moving, but how does it get lift if it is prevented from accelerating from 0 to 1 km/h of ground speed (relative to the real ground—relative to the ground it experiences, it is moving forward at the same speed as the treadmill is moving backward), since until it starts getting lift, airspeed and ground speed are surely effectively equal (wind being too small of a factor)?
A stationary aeroplane on a treadmill will obviously move with the treadmill. I assume an aeroplane moving at like 1 km/h still gets pulled backward by the treadmill.
so, every wheel or ball or any other kind of rolling-thing has rolling resistance, which is how we sum up the total drag on the system. A steel ball bearing on a steel plate will have a significantly lower rolling resistance than, say, a steel cube on that same plate. Tires have some- but not a lot- of rolling resistance.
You can see that in a car, just put it into neutral and watch as you slow down, even on flat ground. Plane wheels also have rolling resistance. it's just the way our world works. But it's generally ignored because it's hard to model perfectly and in any case pretty negligible relative to the amount of acceleration being put out by modern aircraft engines.
A treadmill will only push an aircraft or whatever else along, with an acceleration that is equal to, or lower, than the rolling resistance. If you try to accelerate the plane faster, it'll 'slip', and the plane will remain largely stationary- like the dishes in the tablecloth trick (if you want to try that at home... make sure the tablecloth doesn't have a hem, heh.)
But, keep in mind you're thinking about the plane relative to either the ground, or the treadmill's belt.
the plane's wings and it's engines are 'thinking' about the plane relative to the air it's moving through. It's the airspeed that generates the lift, and the engine isn't coupled to the wheels, they're just rolling along doing their thing. (aircraft engines work by taking a volume of air and accelerating it. newton's equal-and-opposite does the rest.)
Oh wow thank you. This is genuinely excellent and immensely helpful. I think this bit:
A treadmill will only push an aircraft or whatever else along, with an acceleration that is equal to, or lower, than the rolling resistance. If you try to accelerate the plane faster, it’ll ‘slip’
As well as this video that I found where a pilot explains how under specific but unrealistic conditions you could construct a treadmill that does indeed prevent an aeroplane from taking off,
Really helped solidify my understanding of the problem. So you end up with a situation where the wheels are going to be slipping, just like the slippage created when your hand pushes a toy car on a treadmill.
Thanks!
The key insight is that the force a plane uses to move is independent of the ground, because planes push on the air, not the ground.
Imagine you put a ball on a treadmill and turn it on, what happens? The ball starts to spin and move with the treadmill. Now take your hand and push the ball backwards against the motion of the treadmill, and the ball easily moves in that direction. The force your hand put on the ball is exactly what planes do, since they push on something other than the ground (the treadmill) they have no problem moving, no matter how fast the treadmill is moving.
but how does it get lift if it is prevented from accelerating from 0 to 1 km/h of ground speed
That’s the thing - it is not prevented from accelerating. The wheels are functionally frictionless. That’s why planes have brakes. The plane pushes on the air to move, & the treadmill could accelerate backwards until the plane’s tires explode.
It doesn't matter how you run because ALLIGATORS WON'T CHASE YOU.
I used to live in Florida on the edge of a big lake where my landlord had carved out a lagoon that mama gators used to hatch their broods, so there would often be between 50 and 100 little alligators chilling out in my backyard sunning themselves. For fun I would try to sneak up on one of them and poke it on the head just to watch it and all the others scatter into the lagoon. Everybody I told about this thought I was absolutely batshit crazy, but I knew that at the time there had been something like 5 alligator attacks on humans in Florida since the 1940s, always on little children playing in water (I was obviously a little child mentally but physically I was a 200-pound adult man). So I knew I wasn't risking life or limb doing this. For the record, my sneaking up technique was to stand stock still and only move a step or two towards the gator whenever the wind blew; it seems that the gators just took me for a swaying branch and ignored me.
What made me stop doing this was one day I happened to look down at what I thought was a big log and realized that it was actually the mama gator, about 12' long from tip to tail and probably 2' in diameter at her midsection. I was fairly confident that she wouldn't attack me on land either - but not that confident.
but not that confident.
That's how you bust myths!
Ive told people this many times, we need to create more room for failure. From school, to jobs, to building businesses, to loans, to health.
If we can try something because if we fail we can try something else, we would find a hell of a lot more to care about in this world.
And the most important thing we would care more about is ourselves
Mandatory Dwarf Fortress in every school.
Okay thats it im tired of people commenting about this Dwarf fortress. How much of my soul does it cost? Whats that in hours needed?
Yes. Be ready for the most fun you'll ever experience in a game.
I cannot agree enough with this statement and especially love your closing. We definitely don't tend to be able to take enough time to really care for ourselves and try and fail at new things.