YouTube Classics, Part Deux

[etotheipi]

what the f*ck has happened to my youtube recommendations

 

[etotheipi]

 

[Jarvis323]

 

[nsaspook]

All you can eat is back in Vegas.

 

[Ivan Seeking]

 

[Ivan Seeking]

I think I know the key to how it works. Anyone want to explain?

 

[jbriggs444]

I think I know the key to how it works. Anyone want to explain?

Check out this thread in the Classical Physics sub-forum.

https://www.physicsforums.com/threads/ddwfttw-looking-for-the-least-confusing-explanation.896869/

I recommend reading the entire thing before attempting to add anything. Pretty much everything that could be said has already been said.

 

[Borg]

Here's the tree outside my door and the endless noise associated with it. This has been going on for several weeks and seems to be at a peak right now.

 

[nsaspook]

 

[nsaspook]

Remembering your friend on a Youtube channel.

 

[nsaspook]

 

[nsaspook]

Standard disclaimer inserted. Death, injury , etc ... don't do this at home.

 

[DaveC426913]

I think I know the key to how it works. Anyone want to explain?

The TL;DR version:

Three key facts:

1. A sailboat can sail downwind off wind faster than the wind. (i.e. on a broad reach, it is possible for a sailboat to beat a drifting balloon. (07m30s)
2. This effect can be utilized, although not on the way one might expect. (8m05s)
3. The propeller is not driving the wheels. (This is the key key.) In fact, the wheels are driving the propeller. The propeller is what is pushing the vehicle forward - which is why it can exceed the wind speed. (10m58s).

 

[Ivan Seeking]

The TL;DR version:

Three key facts:

1. A sailboat can sail downwind off wind faster than the wind. (i.e. on a broad reach, it is possible for a sailboat to beat a drifting balloon. (07m30s)
2. This effect can be utilized, although not on the way one might expect. (8m05s)
3. The propeller is not driving the wheels. (This is the key key.) In fact, the wheels are driving the propeller. The propeller is what is pushing the vehicle forward - which is why it can exceed the wind speed. (10m58s).

Let me state that another way: Calculate the maximum speed based on the initial wind speed V.

 

[DaveC426913]

Let me state that another way: Calculate the maximum speed based on the initial wind speed V.

I don't know how I would do that, but wouldn't you need to know how the gadget works (to know what forces are involved) to figure that out?

Anyway, they managed to achieve a much higher v than I assumed. They managed to reach 2.8 times wind speed!

 

[Ivan Seeking]

I don't know how I would do that, but wouldn't you need to know how the gadget works (to know what forces are involved) to figure that out?

Anyway, they managed to achieve a much higher v than I assumed. They managed to reach 2.8 times wind speed!

You simply assign variables for air friction, road friction, blade size, design, and pitch, etc... If you really understand how it works, you can set up the problem. The actual numbers are irrelevant.

The key is to determine precisely how energy is added to the system.

 

[jbriggs444]

You simply assign variables for air friction, road friction, blade size, design, and pitch, etc... If you really understand how it works, you can set up the problem. The actual numbers are irrelevant.

The key is to determine precisely how energy is added to the system.

If you have thrust to drag ratio for the airfoil, that should be enough.

Friction with the ground is irrelevant since one can make the craft as massive as is required to obtain the requisite traction. Friction with the air is irrelevant since one can make the prop as large as required (ignoring materials issues). Blade size, design and pitch are irrelevant if one can distill the performance down to thrust versus drag.

 

[Ivan Seeking]

If you have thrust to drag ratio for the airfoil, that should be enough.

Friction with the ground is irrelevant since one can make the craft as massive as is required to obtain the requisite traction. Friction with the air is irrelevant since one can make the prop as large as required (ignoring materials issues). Blade size, design and pitch are irrelevant if one can distill the performance down to thrust versus drag.

I have seen two pages of arm waving over this and not one equation.

Is this a bar or Physics Forums? Perhaps I took a wrong turn. ;)

Oh yes, and they have to adjust pitch.

 

[jbriggs444]

Is this a bar or Physics Forums? Perhaps I took a wrong turn. ;)

This is General Discussion. In particular, "YouTube Classics, Part Deux".

 

[Ivan Seeking]

This is General Discussion. In particular, "YouTube Classics, Part Deux".

And a thread was linked. ;)

 

[nsaspook]

 

[collinsmark]

Here's an update on the faster than wind, downwind vehicle. For technical discussions, there is already a thread in place for this here: https://www.physicsforums.com/threa...the-least-confusing-explanation.896869/page-3

 

[nsaspook]

 

[Ivan Seeking]

Here's an update on the faster than wind, downwind vehicle. For technical discussions, there is already a thread in place for this here: https://www.physicsforums.com/threa...the-least-confusing-explanation.896869/page-3

Fantastic! He really nails it intuitively in the demo with the wheels and board at the end. And in the first video linked above, she nails it down as to WHAT "gear ratio" is in play.

 

[Ivan Seeking]

It was cool to find this original version of David Bowie singing Space Oddity.

 

[DennisN]

I saw an absolutely fascinating video some time ago.
It's a tour of a modern nuclear submarine (US), including when it it traveling and navigating below the ice sheet in the Arctic. I also thought it was very interesting to hear various members of the crew getting interviewed. And it's interesting from a technological viewpoint too, of course, submarines are quite impressive vehicles.

Another fascinating video from the same channel and about the same submarine:

How to Surface a Submarine in the Arctic Ocean - Smarter Every Day 260

 

[DaveC426913]

How to Surface a Submarine in the Arctic Ocean - Smarter Every Day 260

Oh my goodness. Is there some subset of that 42 minute video that maximizes the ratio of informativity per unit time?

 

[DennisN]

Anyone into very spicy food?

I just saw a funny video where the two spice-eating legends Chili Klaus (Denmark) and Sean Evans (US) try the second hottest pepper in the world, the Carolina Reaper with a Scoville scale of 1'569'300 (no 1 is a pepper called Pepper X). The two fellows are very used to hot food, and their reactions are a testament of the potency of these little beasts of fruit.

Sean Evans and Chili Klaus Eat the Carolina Reaper, the World's Hottest Chili Pepper

 

[BillTre]

I used to like hot foods a lot, but not so much now. Maybe I've burned out a bit.
My son carries on the tradition of liking hot foods, which my Dad also had.

I find these heat rating systems interesting. Its like psychophysics (measuring internal sensory responses to know chemical/physical conditions). Thus, a quantitative relationships between the physical world and the psychological world of internal sensation.
The Scoville measurement involves diluting until not senseable.

Chemical/physical measurements of specific chemicals might be misleading, due to assumptions about the chemical nature of the molecules responsible for the "heat".
I read about one of the new peppers that was studied a few years ago. It had a different taste and caused people's tongues to vibrate.
Could be a different chemical working via different pharmacological mechanisms.

 

[collinsmark]

Anyone into very spicy food?

I just saw a funny video where the two spice-eating legends Chili Klaus (Denmark) and Sean Evans (US) try the second hottest pepper in the world, the Carolina Reaper with a Scoville scale of 1'569'300 (no 1 is a pepper called Pepper X). The two fellows are very used to hot food, and their reactions are a testament of the potency of these little beasts of fruit.

Sean Evans and Chili Klaus Eat the Carolina Reaper, the World's Hottest Chili Pepper

I used to be a connoisseur of hot sauce, of sorts.

Today, I still eat a lot of spicy foods, and consistently use Tabasco, Sriracha, Valentina, and now Frank's RedHot, that I pretty much just slather on anything, and always have on hand. But I don't get into the really, really hot stuff like I used to.

You'll notice in the video there is a bottle of Mad Dog 357 on the table. That stuff is very hot, but the company had released a much, much hotter version called "Mad Dog 357, Silver Collector's Addition" that boasted 6 million Scoville units. It comes with a (decorative) bullet, and I had to sign a waiver to buy a couple bottles. I still have a spare, unopened bottle, just in case.

I stopped using the really, really hot stuff though, after one time where I inadvertently, albeit temporarily (maybe a few minutes), lost all feeling in my feelings (and various body parts too).

 

[ergospherical]

 

[Ivan Seeking]

I used to be a connoisseur of hot sauce, of sorts.

Today, I still eat a lot of spicy foods, and consistently use Tabasco, Sriracha, Valentina, and now Frank's RedHot, that I pretty much just slather on anything, and always have on hand. But I don't get into the really, really hot stuff like I used to.

You'll notice in the video there is a bottle of Mad Dog 357 on the table. That stuff is very hot, but the company had released a much, much hotter version called "Mad Dog 357, Silver Collector's Addition" that boasted 6 million Scoville units. It comes with a (decorative) bullet, and I had to sign a waiver to buy a couple bottles. I still have a spare, unopened bottle, just in case.
View attachment 287322

I stopped using the really, really hot stuff though, after one time where I inadvertently, albeit temporarily (maybe a few minutes), lost all feeling in my feelings (and various body parts too).

Blair's 16 Million Reserve - pure crystalized capsaicin
https://www.chilliworld.com/blairs-16-million-reserve

You don't actually adjust to hot hot hot. You are really just damaging the sensors in your mouth.

 

[nsaspook]

 

[Ivan Seeking]

Well someone sure put their bigfoot in their mouth.

Hey honey, let's scare the bejeezuz out of the kids with this costume. They will forget all about the cake! They'll just be glad to be alive. Then we yell, Happy Birthday!

 

[Ivan Seeking]

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