Randomness

[Jimmy Choo]

This was a thing this morning on my way to work

https://www.thetelegraphandargus.co.uk/ ... rber-shop/

It genuinely looks like a cartoon image of what happens when a car goes into a building. Seen CCTV footage of the actual incident itself, doesn't look like they were hanging around when they literally failed to notice the fact that the road ends into a roundabout...

https://www.leeds-live.co.uk/news/leeds ... g-20837391

locked up and still hits the building at a squillion mph!

[Beany]

Bear in mind that's CCTV footage running at about 1.5-2x speed. Still, lucky it didn't go about six inches to the right, would have taken out a structural wall...

[Jobbo]

[mik]

[nuttinnew]

dubbing Alan Partridge

[nuttinnew]

[ZedLeg]

I’m not even sure what this is supposed to be

[jamcg]

I’m not even sure what this is supposed to be

Wtf????!!!!!

[nuttinnew]

[nuttinnew]

[RobYob]

One of the most counterintuitive things I've ever seen. It's been around for a while but this is a good video of the working vehicle.

Faster down wind than the wind without tacking.
Around 18:00 is the attempt at explanation....

Back to this, Steve Mould has done a video now too:

Both sides now putting their money where their mouths are
https://www.iflscience.com/physics/a-yo ... f-physics/
$10k to the charity of choice for the winner.

[Peterlplp]

The story behind that one:

[mik]

[RobYob]

One of the most counterintuitive things I've ever seen. It's been around for a while but this is a good video of the working vehicle.

Faster down wind than the wind without tacking.
Around 18:00 is the attempt at explanation....

Back to this, Steve Mould has done a video now too:

Both sides now putting their money where their mouths are
https://www.iflscience.com/physics/a-yo ... f-physics/
$10k to the charity of choice for the winner.

Crikey, already conceeded in favour of the downwind faster than the wind. I was looking forward to some more detailed videos of some experiments.
https://twitter.com/veritasium?ref_src= ... r%5Eauthor

[mik]

I’m still confused As all these vids are focussed on how a sail/wing allows you to generate a force in another direction. Which is fine, but then they advise this isn’t how the craft works - it is pushed by the wind (on what? The uprights holding the fan?) which drives the wheels which drive the fan. So most of the theory is irrelevant….??

[RobYob]

I’m still confused As all these vids are focussed on how a sail/wing allows you to generate a force in another direction. Which is fine, but then they advise this isn’t how the craft works - it is pushed by the wind (on what? The uprights holding the fan?) which drives the wheels which drive the fan. So most of the theory is irrelevant….??

Same, there's not a single explanation I've yet seen that I can intuitively fully follow.

One good analogy I read on Facebook was of two ice racers that can tack downwind faster than the wind dragging a third sail-less racer between them that will as a result be going downwind faster than the wind.

So the wheel drives the tacking motion...

But the whole "is it a fan, is it tacking sails" is badly explained all round.

[Jobbo]

I like the ice racer analogy; it's that sort of thing which makes it possible to comprehend the solution even if it remains unintuitive. The professor's maths haven't made it more understandable for me but I'll revisit that.

The thing which feels odd to me is that if you can go faster than the wind, you could in theory accelerate and then maintain a slow speed in still air provided you get a push to start with. But that's clearly not possible.

Good to see the prof's objection was to Derek saying it worked as a fan, rather than a full denial, anyway

[Swervin_Mervin]

As someone that sometimes struggles with explanations of engineering concepts (I have to see to get a feel for the understanding) it seems to me like it should be a mix of both concepts i.e. both tacking sail and fan, and that the mix of the two varies with speed, moving more towards the latter once above wind speed.

[nuttinnew]

The story behind that one:

Ta

[ZedLeg]