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It’s still the explanation on NASA.gov https://www.grc.nasa.gov/www/k-12/UEET/StudentSite/dynamicso...
It’s still the explanation on NASA.gov https://www.grc.nasa.gov/www/k-12/UEET/StudentSite/dynamicso...
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/lif...
Earlier quoted context omitted.
Simplified explanations of how electrical current flows in conductors comes to mind. Water analogies, for example.
The water analogy is great. Not only are the basic equations exactly the same but it's easy to visualise. I don't see why you wouldn't like it. The basic equations are actually identical for a lot of domains, including rotational motion which gave rise to the Spintronics game.
I recently encountered this in a sailing class when the teacher was explaining how "pull-mode" works in sailing, where the wind is coming from ahead of the vessel and pulls the sails rather than pushing them. I knew this theory to be debunked and yet couldn't work out the answer from non-debunked physics (and certainly didn't want to disrupt the class by arguing physics with someone who's been sailing for 50+ years -…
Maybe state of the art hydrofoiling boats, cats and some quite large monohulls, but maybe that's what you meant by modern. Most sailboats built today have a pretty low top speed (due to hull speed limitations) relative to wind speed - monohulls often max out around 5-6 kts aren't going to be faster than the wind pretty much ever
So what is correct explanation? Is there a TLDR?
> Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing. The difference in pressure creates a force on the wing that lifts the wing up into the air.
Then I read [2] which corrects that view:
> “What actually causes lift is introducing a shape into the airflow, which curves the streamlines and introduces pressure changes – lower pressure on the upper surface and higher pressure on the lower surface,” clarified Babinsky, from the Department of Engineering. “This is why a flat surface like a sail is able to cause lift – here the distance on each side is the same but it is slightly curved when it is rigged and so it acts as an aerofoil. In other words, it’s the curvature that creates lift, not the distance.”
This is still not very satisfying, as it fails to show HOW curvature causes lift. Maybe there is no simple explanation...
[1] https://www.grc.nasa.gov/www/k-12/UEET/StudentSite/dynamicso...
[2] https://www.cam.ac.uk/research/news/how-wings-really-work
So what is correct explanation? Is there a TLDR?
“Just like the "explanation" of seasons by the Earth's changing distance to the Sun, or textbook pseudo-explanations of history, like the "crisis" over the discovery of irrationals, or Maxwell's "mathematical" reason for adding an extra term to Ampere's equation.” Love it! Anyone have any others?
Simplified explanations of how electrical current flows in conductors comes to mind. Water analogies, for example.
1) DC; 2) low frequency AC; 3) Radio frequency circuits
With DC, the water in pipes analogy is close enough to be useful.
With low frequency AC, like mains electricity at around household voltages, there are additional considerations to make the water in pipes analogy to be useless enough we generally require people to be licensed to work with it.
Radio frequency electronics is indistinguishable from magic.
No idea why you would provide the equal transit time theorem to students, it makes such a low amount of sense that you're inevitably going to get your students extremely confused if they are paying any attention at all. "Why does the air have to transit in the same time period?" "But _why_ is the air moving over the top faster? Weren't you going to tell me how a wing works?" Etc etc etc It is the worst kind of lie-to…
Because otherwise it would leave holes in it where one side moves too fast before joining back up.
It makes more sense if you imagine air to be incompressable.
So what is correct explanation? Is there a TLDR?