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  • Meh, I strolled over, read though, and found absolutely nothing of value at the "talk rational" forum. What a waste of time, space, and pixels.- utter rubbish.

Topic: Direct Down Wind Faster Than The Wind (Read 14116 times) previous topic - next topic

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  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #800
I'm not sure, but believe I have  watched kite surfers go downwind faster than the wind, by using the kite in clever ways.

Is that possible?

I mean, they are going ddwfttw, but the kite is moving all over
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #801
When kitesurfing we can tack downwind faster than the wind, but we can't go DDWFTTW.  In order to do that you have to have a way to exploit the energy of the wind over the water.  While going directly downwind you can only apply a side force on the water - not a force that opposes the true wind direction.

Re: Direct Down Wind Faster Than The Wind
Reply #802
The treadmill experiment shows that wind isn't even the driving force, it's the cart moving that allows it to outrun the energy source, except it doesn't outrun it, which is why it's such a mindfuck

Wind or treadmill, the cart goes faster than the source of the energy, but it doesn't outrun it, nor is it magic

Stop the source of energy and the cart stops

It shows no such thing. The cart on a treadmill is indistinguishable from a cart outside. The energy for the cart comes from slowing the air mass down relative to the ground. The energy source for the wind on the treadmill is the AC plug and it is the sun for wind outside but that has nothing to do with the cart.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #803
The cart on a treadmill is indistinguishable from a cart outside.
Nobody recently has claimed it isn't.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #804
Do I really need to show you the fucking numbers??

There is little if any doubt that humber drove the numbers.  And that's no surprise.  Without humber it was mostly just a group of smart people that had come to understand the thing and were now discussing some of the finer details (some of which are really interesting).  But number of posts or pages doesn't tell us that humber had a clue.  On the contrary, people literally kept responding to him because they just couldn't believe he was as stupid as he appeared.  Hell - that's still being debated in the posts directly above.  Personally I think he was truly that stupid.  But I also think he was a truly horrible person - like Trump.  And that's why I stopped responding to him years ago.  I will admit I was thankful for the others that continued to call him out on his insults and lies.

If in fact humber was as clueless about physics as he came off, then you're wrong about one thing... you know more physics than him.  But then so does Bob - my hermit crab.



The real question about Humber is whether the poster was genuine or not. If genuine, then I would say he was insane. The concepts of intelligence, stupidity etc are meaningless really when applied to the insane. So if not genuine, then clearly quite clever (to manage the trolling regardless of any understanding of the topic), if genuine, clearly insane. Of course the insanity could be overlaid on a relatively stupid or relatively intelligent person.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #805
In defense of Humber (I know I know, calm down), he did have a valid point in that the wind blowing on you is not exactly the same as being on a treadmill.

Quote
JB says that I can't tell the wind of his porch on a belt from the real. If the wind on my real porch changes, I see no acceleration, but on JB's they are directly related.
http://www.internationalskeptics.com/forums/showpost.php?p=4293932&postcount=2786

That's a valid point.  Because wind in reality does change, it varies, but to "feel" slight changes in the wind on a treadmill, you would feel yourself moving.  It isn't exactly the same.

Steady state, exact wind, of course you couldn't tell.  But to simulate real wind with a treadmill woul mean changing the speed of it slightly, and nobody would mistake that for being in a real wind.

It doesn't matter in regards to the cart, but he did have a valid point.

"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #806
And yes, I did reread that entire thread.  Skipped over a bunch of long posts, but it was fascinating in hindsight.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #807
In defense of Humber (I know I know, calm down), he did have a valid point in that the wind blowing on you is not exactly the same as being on a treadmill.

It doesn't matter in regards to the cart, but he did have a valid point.


He had a point. Not a valid point though.

There are all kinds of differences which are not relevant, the point is that the treadmill and wind outside are indistinguishable in all ways relevant to the carts function.  Any focus on nonsense like vibrations and inconstant wind speeds and other things which obviously, (if one is not hard of thinking), impair the ability of the cart to go ddwfttw are rather pitiful attempts at creating a red herring.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #808
There are all kinds of differences which are not relevant,
I said that it didn't matter in regards to the experiment.  In regards to a perfect steady wind you can't tell the difference.  But in the real world the wind isn't perfect, so a treadmill is not the same as being in a real wind.  In fact, it can't be made to replicate actual wind, because any change in the treadmill will be felt by an observer, unlike standing on steady ground with the wind blowing and gusting.

This doesn't matter for the cart, but it would matter for an observer on a treadmill, or any moving device.  You can tell that you are moving when there is a change in velocity.  It's why the point that being on a treadmill or ship or in a car isn't exactly the same as being on solid ground feeling the wind.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #809
...the treadmill and wind outside are indistinguishable in all ways relevant to the carts function.

I think perhaps a more important point is that the air over a treadmill IS wind.  It doesn't simulate wind.  Sure the wind on the bay may be different than the wind in front of my house, which may be different than the wind relative to the treadmill belt.   Gradient will vary from one day to the next or one site to the next, as will the period and intensity of gusts and direction shifts.  But that doesn't make the treadmill's wind any less real.  When the cart works on the treadmill - it's actually working - not just proving that it can work.
  • Last Edit: June 16, 2017, 12:21:40 AM by spork

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #810
I think perhaps a more important point is that the air over a treadmill IS wind.  It doesn't simulate wind. 
That's just not true.  For the purpose of the cart experiment, it certainly is a valid experiment.  Because for an object moving on a treadmill, or aircraft carrier, or a car, there is felt a wind, but it does not meet any definition of wind as it is defined.

It would be like claiming riding a bike creates wind, because you feel a wind on your face.

This is a minor point, and does not mean anything in regards to the cart.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #811
This is illustrated by using a huge moving platform, like an aircraft carrier, to do the experiment. To the cart, there is wind. But an aircraft carrier does not create a wind.  It causes objects on it to experience a wind.

"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #812
But an aircraft carrier does not create a wind.  It causes objects on it to experience a wind.

Which is moving - the aircraft carrier or the air?

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #813

Which is moving - the aircraft carrier or the air?

Like all motion, it depends on where you observe from. Certainly from the POV of being on the deck, it seems liken the ship is moving.  If there is no wind at all, we see it as the ship moving, not the air.  but the cart doesn't care, it feels like a wind is blowing, and that is what matters to the cart.  From the carts POV, the air is moving.

To say the air is moving would be absurd.  We know the apparent wind is from the ship steaming along. 
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #814
To say the air is moving would be absurd.

Wrong.  There is no such thing as absolute motion.  It is *exactly* as accurate to say the air is moving as it is to say the ship is moving.  It's not a matter of what it "seems" like.

That said, I do not care to get into another months long pissing match with you.  I've said my bit.  It's correct.  So have at it with as many insults as you like now.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #815
It is *exactly* as accurate to say the air is moving as it is to say the ship is moving.  It's not a matter of what it "seems" like.
movement
an act of changing physical location or position

By definition when something moves, it changes location, or position.  An object moving through still air is obviously moving.  If the air is still, not moving in relation to the ground, and you ride a bike (or an aircraft carrier) through the still air, this does not somehow allow us to claim all the air is now moving.  Because it's not.

Of course the moving object experiences the air (and the entire world) as moving,  But it's absurd to claim the air (or the ground) is moving.

You could do a similar thing, and move yourself at the exact speed of an actual wind, and then claim the wind is not blowing.  It's just as absurd.  Of course from the POV of a moving object everything else is moving, but we don't say the world moves when we drive to the store.

It doesn't matter for the cart experiment, because the cart experiences a wind on the treadmill, or aircraft carrier, since the relative motion of course causes a wind.  But it does no good to claim the air is moving over the treadmill, since it is not.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #816
It is *exactly* as accurate to say the air is moving as it is to say the ship is moving.  It's not a matter of what it "seems" like.
movement
an act of changing physical location or position

By definition when something moves, it changes location, or position.  An object moving through still air is obviously moving.  If the air is still, not moving in relation to the ground, and you ride a bike (or an aircraft carrier) through the still air, this does not somehow allow us to claim all the air is now moving.  Because it's not.

Of course the moving object experiences the air (and the entire world) as moving,  But it's absurd to claim the air (or the ground) is moving.

You could do a similar thing, and move yourself at the exact speed of an actual wind, and then claim the wind is not blowing.  It's just as absurd.  Of course from the POV of a moving object everything else is moving, but we don't say the world moves when we drive to the store.

It doesn't matter for the cart experiment, because the cart experiences a wind on the treadmill, or aircraft carrier, since the relative motion of course causes a wind.  But it does no good to claim the air is moving over the treadmill, since it is not.

I realize now that this guy is at least as loony as our two Hs.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #817
That adds nothing to the discussion.

"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #818
That adds nothing to the discussion.

We had this discussion a long time ago.

Your definition you used refers to "changing location" which means that it is keyed to a reference frame to define a location and time.

Motion is defined in a technical (physics sense) as a change of location over time with regards to a specific frame of reference which would typically include a coordinate system and metric to determine where a location is.  Once that is defined, then changing location with respect to the coordinate system or reference frame locations with respect to time is "motion" with respect to the reference frame.

So once one picks an inertial reference frame (or one reasonably close to inertial), then air moving with respect to that reference frame is "wind" in that reference frame where it might only be still air in another or blowing in a different direction and speed in a third.

The point is, there is no magic "wind" or "no wind".  If there is a defined reference frame and a gas, then it is either (bulk) moving or not moving with respect to the frame which would make it a wind.  Any other definition leads to contradictions.  And there is no "absolute" or "special" reference frame, just preferred or perhaps an unspoken "default frame" such as one stationary with respect to the ground.

Windgrins :grin:
  • Last Edit: June 19, 2017, 05:49:53 AM by windgrins
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #819
We had this discussion a long time ago.
No doubt.
Your definition you used refers to "changing location" which means that it is keyed to a reference frame to define a location.
It's not "my definition", it's how the word is defined

The problem may be language.
There is no such thing as absolute motion.  It is *exactly* as accurate to say the air is moving as it is to say the ship is moving.
That's just not true.  They are not exactly the same.  If a vehicle starts moving, ship or car or whatever it is, it's not accurate or exactly the same to claim the rest if the world is moving.  Because it's just not. From the POV of a moving observer the entire Universe is moving, but claiming the two are the same is absurd.

To say they are is to lose sight of reason and logic.

For the purpose of the cart it's the same thing, the virtual wind is real in the sense it allows the cart to go ddwfttw on a treadmill, or a giant ship, that's not disputed.




"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #820
We had this discussion a long time ago.
No doubt.
Your definition you used refers to "changing location" which means that it is keyed to a reference frame to define a location.
It's not "my definition", it's how the word is defined

The problem may be language.
There is no such thing as absolute motion.  It is *exactly* as accurate to say the air is moving as it is to say the ship is moving.
That's just not true.  They are not exactly the same.  If a vehicle starts moving, ship or car or whatever it is, it's not accurate or exactly the same to claim the rest if the world is moving.  Because it's just not. From the POV of a moving observer the entire Universe is moving, but claiming the two are the same is absurd.

To say they are is to lose sight of reason and logic.

For the purpose of the cart it's the same thing, the virtual wind is real in the sense it allows the cart to go ddwfttw on a treadmill, or a giant ship, that's not disputed.

Sorry,  It is indeed true.  As long as the reference frame chosen is unaccelerated (during the course of any experiment), it constitutes an Inertial reference frame and is equivalent to any other chosen IRF for the purpose of experiments.  This is the basis of modern physics so isn't really in dispute.

A vehicle that "starts moving" does not constitute an inertial frame of reference.  It is consistent with an inertial frame once it reaches a steady velocity and the frame was (is) defined as moving with that velocity.  Then any deviation from that velocity is "motion" of the platform with respect to the frame.

In fact, it is a loss of reason to say that the inertial frame is in any way special for the ground, and it is perfectly rational to say that the rest of the world is moving with respect to our frame defined by the constant velocity of the ship or train (as long as it remains constant velocity) (and in fact with respect to the sun, the earth is moving, as well as everything on it).

The problem isn't really the language.  The problem is that the language doesn't concisely capture modern Newtonian physics (much less relativistic physics).  The problem is that most people (like Humber) assume that the earth somehow defines a "special" or "absolute" rest reference frame which is fundamentally wrong.

So the treadmill belt (with its average velocity), can be used to define an inertial reference frame and the air in the room is a "wind" with respect to that frame (which is stationary with an instantaneous point chosen on the top of the belt.  The belt itself is not inertial since it whips around (accelerates) on each end but the frame of reference that is defined to move consistently with a point chosen with a point on the top of the belt is.  The frame continues with the motion of the belt, or instantaneous point chosen on the top of the belt (with respect to the floor) even though any point chosen on the top of the belt doesn't (when it goes over the end rollers).

Like it or not, that's the way the universe actually works (to the best of our knowledge).  The idea that motion is anything but relative (to an arbitrary inertial reference frame) is actually what is absurd.  And the reason is that any other belief is inconsistent with reality as demonstrated by countless actual physics experiments.*

*Note that this commentary ignores the "warping of space and time" due to relativistic physics of relative motion and gravitational changes of space itself.  It is intentionally limited to "Newtonian physics" which are fine for the purpose of these discussions but don't capture the actual details of spacetime, matter, and motion in its entirety so is by definition, slightly limited.

Windgrins :grin:
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #821
I can see how there is confusion here.  You just defined a stationary point (for the point of view for the reference frame), as a moving point.
It is consistent with an inertial frame once it reaches a steady velocity and the frame was (is) defined as moving with that velocity.

You just wrote these words

" the frame was (is) defined as moving with that velocity."

I quite understand from a physics POV that a moving point can be considered an unmoving point for the purpose of science, because that's how a mental construct works.  The reference point is a mental construct, but in order to define it, you had to explain it is a moving point.  Because it is.

That's also true for a point on the "unmoving" surface of the planet.  The difference is the rest of the planet isn't moving in relation to a fixed point on the surface if the planet (even as the rest if the Universe is)

That's why the two are not exactly the same.  To establish a POV while not moving is simple. A moving POV is not.  You have to have your unmoving reference frame move at the exact velocity of something that is moving, in relation to the rest of the planet.  (simple example, obviously space time itself is another matter)


  • Last Edit: June 19, 2017, 07:32:32 AM by F X
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #822
So the treadmill belt (with its average velocity), can be used to define an inertial reference frame and the air in the room is a "wind" with respect to that frame (which is stationary with an instantaneous point chosen on the top of the belt. 
That doesn't make any sense at all.  You are defining your POV as stationary, which can't be true.  Only a moving point on the belt would experience "wind".  It's why a larger belt would show how the cart behaves, at first moving and feeling a wind, then accelerating until it is at wind speed, then moving faster than the wind, by advancing up the belt.

Using an imaginary treadmill the size of a lakebed would be even better.  The cart would behave as in a steady wind, and there would be no doubt about it.

It's probably why the small treadmill screws with some minds, because they can't understand how there can be wind when the cart isn't "moving" on the treadmill.  But of course if it is staying in one place, it's moving as fast as the treadmill.  It's a brain bender for some.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #823
I can see how there is confusion here.  You just defined a stationary point (for the point of view for the reference frame), as a moving point. quote author=windgrins link=msg=95384 date=1497880266]
It is consistent with an inertial frame once it reaches a steady velocity and the frame was (is) defined as moving with that velocity.


You just wrote these words

" the frame was (is) defined as moving with that velocity."

I quite understand from a physics POV that a moving point can be considered an unmoving point for the purpose of science, because that's how a mental construct works.  The reference point is a mental construct, but in order to define it, you had to explain it is a moving point.  Because it is.

That's also true for a point on the "unmoving" surface of the planet.  The difference is the rest of the planet isn't moving in relation to a fixed point on the surface if the planet (even as the rest if the Universe is)

That's why the two are not exactly the same.  To establish a POV while not moving is simple. A moving POV is not.  You have to hve your unmoving reference frame move at the exact velocity of something that is moving, in relation to the rest of the planet.

No,  you have it all wrong.

I only used that language to explain it.

I could have stated:

"The treadmill is operating smoothly and continously.  Pick a point on its upper surface at a point in time (when the point is on the upper surface) and define a reference frame that is stationary with respect to this point at the time chosen.  From then on, the reference frame is defined even though the point will soon whip around the rollers. The frame itself remains inertial (unaccelerated)."

Note that there is no mention of "motion" even though the "floor" upon which the TM chassis is resting is moving with respect to the chosen frame (as well as the rest of the earth).

Which is why I can have a reference frame in a constant speed aircraft in smooth air that I reference everything to including my champagne pour.  I don't have to worry that the earth 40K feet below is moving at 550 mph with respect to me.

Windgrins :grin:
Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.

Re: Direct Down Wind Faster Than The Wind
Reply #824
So the treadmill belt (with its average velocity), can be used to define an inertial reference frame and the air in the room is a "wind" with respect to that frame (which is stationary with an instantaneous point chosen on the top of the belt. 
That doesn't make any sense at all.  You are defining your POV as stationary, which can't be true.  Only a moving point on the belt would experience "wind".  It's why a larger belt would show how the cart behaves, at first moving and feeling a wind, then accelerating until it is at wind speed, then moving faster than the wind, by advancing up the belt.

The reference frame defined by definition is inertial.  It isn't stationary or moving unless you reference it to something else.  It is simply an inertial reference frame which one can reference any movement or position with respect to.  For example, the floor of the room is moving with respect to this IRF.

You have it backwards on the object in the defined IRF of the belt top and the wind it is in:

If a object with no wheels (say a lego batman holding a small flag) were placed on the surface of the operating TM,  (before it falls off the end), it will experience a wind with windspeed of the set speed of the belt blowing from the direction of the back of the TM and his flag's blowing would be consistent with that. (note that the upper surface of the TM is stationary in the defined IRF).  Lego batman was "stationary" in the defined reference frame while he was on the upper surface of the belt with a wind blowing.   The DDWFTTW cart (stationary in the room but rolling on the belt and with respect to the belt referenced IRF) will be moving at windspeed with the wind and will experience no relative wind but will be in motion wrt the defined IRF.

Windgrins :grin:





Lunatic Fringe, I know you're out there.  You've got to blame someone for your own confusion.