Split Thread The validity of classical physics (split from: DWFTTW)

[ThinAirDesigns]

So here's the latest update (with Sol responding):

Members willing to answer some questions from a basic physics text:

Brian-M: YES
Christian: YES
Clive: YES
CORed: ?
fredriks: ?
H'ethetheth: ?
humb: HELL YEAH
humber: NO
JB: ?
jjcote: YES
John Freestone: YES
Mender: YES
sol invictus: YES
spacediver: ?
spork: YES
subduction zone: YES

I all in. (but hoping if need be I can use one of my lifelines to phone a goldfish)

JB

 

[spork]

...he told me he wasn't impressed and could easily "ace" my argument from authority, if he so chose, which he didn't, in case you were wondering.

I think it's safe to say that no one pays any attention to humber's wild claims and insults. I don't even understand half of his insults as they seem to be as broken and cryptic as the rest of his responses. It occurs to me that it's probably not possible for him to participate in our little physics exercise, because the answers would have to be short and responsive - as in a yes/no, number, or multiple choice. It wouldn't be possible to tally random stream of "consciousness" responses.

Nevertheless, here's the current standing:

Members willing to answer some questions from a basic physics text:

Brian-M: YES
Christian: YES
Clive: YES
CORed: YES
fredriks: ?
H'ethetheth: YES
humb: HELL YEAH
humber: NO
JB: YES
jjcote: YES
John Freestone: YES
Mender: YES
Michael C: YES
sol invictus: YES
spacediver: ?
spork: YES
subduction zone: YES

Still humber is the one guy that knows everything, and yet the one guy that can't answer some very basic questions. To some that would seem bizarre.

 

[mender]

Humber, back to your diagrams for a moment.

Let's review the basics in both cases because the baseline has to be correct or your illustrations won't apply. In the realwind case, the air moves at a constant 10 m/s at all times, and the surface underneath the air moves at 0 m/s at all times. In the treadmill case, the air stays at 0 m/s at all times, and the belt speed moves at a constant 10 m/s at all times. The only speed change that happens in either set is that of the observer. The movement of the observer is separate from the movement of the air and the surface, and doesn't affect (for our purposes) the movement of either the air or the surface.

The 10m/s wind is that generated by observer motion. So it is OK.

Good. You are agreeing that the wind is generated completely by the movement of the observer on the belt. That means that you agree that the air in the treadmill case is not moving, only the belt and the observer to get that 10 m/s wind. To get your diagram to agree with what you are saying, you'll need to erase the extra 10 m/s wind in your lower left diagram. Otherwise, the diagram doesn't agree with your numbers.

Your diagram needs to agree with what you are saying to be valid.



Also, rather than argue about 6 m/s vs 4 m/s for the flow speed, why don't we make it simple and say that at some point in the gradient, the speed change will be 5 m/s. That way you can use 5 m/s in all the cases for now. Sound reasonable? You can change to those numbers without altering the validity of your diagrams. That should help.

Humber, if you really are interested in getting this right, do these simple things. It is vital that your diagrams reflect what it actually going on in both sets.

 

[sol invictus]

I'd like to see humber fill in the blanks in John's diagram...

[qimg]http://www.internationalskeptics.com/forums/imagehosting/22697497348179d162.bmp[/qimg]

 

[RossFW]

Hey Sporky,

Do I get to play??

 

[RossFW]

Humber,

I've been away with work for a couple of days (Hamburg, beutiful but bloody cold!!), and, given time to reflect, I realise you have been right about everythiing.

As such, I now have a problem I hope our newly melded outlook can fix:-

It about Kites.

I have a kite that flys just fine if I'm standing still and the wind is 10M/s.

Thing is, it ALSO flys if there is NO wind and I RUN at 10M/s.

I'm also PRETTY SURE that if I had a long treadmill that went at 10m/s and stood on it, towing the kite, it would also fly.

There must be a problem with my perception, as these things obviously can't be true.

For one, in the first instance it's a REAL wind, where the others aren't, so there's no way I could model the kites performance in 10m/s REAL wind by pulling it through still air at 10m/s, right?

The last one can't be true, because I'm not even running on a REAL road, but on a treadmill, and that's NOT a road!!

Thirdly, and most importantly, there is the issue of KE.

The first kite has no KE in any frame, as it is not moving wrt the earths surface. In the second two, it does.

Now we established (or at least you SAID it many times) that an object with no KE can't model on that has some, so I assume the reverse is also true?

Trouble is, the damned kite still insists on flying.

Can you tell me where I've gone wrong?

 

[Clive]

Also, rather than argue about 6 m/s vs 4 m/s for the flow speed, why don't we make it simple and say that at some point in the gradient, the speed change will be 5 m/s. That way you can use 5 m/s in all the cases for now. Sound reasonable? You can change to those numbers without altering the validity of your diagrams. That should help.

Good grief mender! You're not trying to lure humber into being accidentally correct are you? It's a cunning thought but not nearly cunning enough because he's much more like an old trout behind a rock than a goldfish drifting downstream.

You're overlooking some subtle details. What you're doing is actually very like suggesting that the energy converted to heat in an non-elastic collision doesn't depend on the materials involved. I can see much more clearly now where humber is coming from. 5 is not even shown in the diagram in John's most recent post. That's quite likely to be definitely because he might have realised what you haven't yet. Here let me explain again. Expecting 5 to work would imply the relative boundary flows are simultaneously different (CCW) and the same yet (CW) regardless of the frame you're observing from within. All frames are symmetrical as we've agreed many times before but you can't suddenly use a created datum that always generates the same values. That would be introducing an equals sign in your assumptions to prove equivalence. No! You will always observe at a logical contradiction against the CCW flow. No, and is not a valid choice either. Look at the thrid diagram where the distance is shown. This is much clearer. John also omitted 3 for some reason in his, so perhaps something is still, but that has never been my contention. Try stricking with asymmetrical flows. I'm being figurative but the difference is only notional in this case. Correct analysis will always confirm the strength of the real wind and the vapidity of the treadmill. Humber cannot possibly use 5 for all these reasons and more. That would be a prime case of mixing frames even though nominal and of course all values exist in any real valued infinite graduation. He's far too clever to be that stupid anyway. Do you see it now?

 

[Ziggurat]

Trouble is, the damned kite still insists on flying.

Can you tell me where I've gone wrong?

Obviously your kite is broken. I suggest you get a new one.

 

[spacediver]

Count me in:

Members willing to answer some questions from a basic physics text:

Brian-M: YES
Christian: YES
Clive: YES
CORed: YES
fredriks: ?
H'ethetheth: YES
humb: HELL YEAH
humber: NO
JB: YES
jjcote: YES
John Freestone: YES
Mender: YES
Michael C: YES
sol invictus: YES
spacediver: YES
spork: YES
subduction zone: YES

 

[Clive]

As such, I now have a problem I hope our newly melded outlook can fix:-

It about Kites.

I have a kite that flys just fine if I'm standing still and the wind is 10M/s.

Thing is, it ALSO flys if there is NO wind and I RUN at 10M/s.

I'm also PRETTY SURE that if I had a long treadmill that went at 10m/s and stood on it, towing the kite, it would also fly.

No RossFW, you have much to learn before joining the dark side. It is so simple so I will save the master from your mindless distractions and answer in his stead.

In the first case the WIND powers the kite. This is a KITE really FLYING.

In the second case the Earth passes kinetic energy (yes it IS moving) up through your pumping legs, to body and arms, along the string and into the kite (where some is stored in case it needs to fall later, no, possibly). This is not true kite flying. There are differences and you would do well to observe them. The kite is planing through the air.

The third case is similar to the second but a belt is not a road. How many times must this be said. I (and the master) are getting tired. Haven't you been listening? The motor of the treadmill is the power source here. Again there are difference but you have not looked have you?

Try harder. Start again. 10 - 3 might be only a distance, but you're looking for more velocity here.

 

[jjcote]

In case anyone is curious, here's the reasoning for why I chose 6 m/s as the speed of the air in the boundary layer (at some arbitrary distance from the surface). There had been some earlier posts that used 7 m/s for this value. I had thought about using 5 m/s, but I though there was some merit in not setting it at half-speed, so as to make clear which was the difference between this speed and the free stream flow, vs. this speed and the surface. And I made it 6 m/s so that the difference would be 4 m/s, and the time until the smoke puff went by would be 2.5 s, instead of the more unwieldy 3.33333 s.

 

[Clive]

In case anyone is curious...

So it's all your fault then! Just think how much more quickly this conundrum could have been "resolved" if you'd gone with 5. How would the universe have unfolded in that case?

 

[CORed]

Obviously your kite is broken. I suggest you get a new one.

I don't think the kite is broken, but it is wrong and backwards. Also, if he can run 10 m/s, he should try out for the olympics.

 

[Clive]

I don't think the kite is broken, but it is wrong and backwards. Also, if he can run 10 m/s, he should try out for the olympics.

You are correct CORed about it being wrong and backwards. Well done. Some recent back of the envelope scribbling in a lounge confirmed the boundary layer reversal exists with the dragged planing kite also (as I always suspected) on its sunny side. The flying kite is okay as you'd expect. After a short map and more neds a detailed force analysis The others need to understand the boundary layer reversal before we can progress any further. There are enough questions on the table already. It is not trivial ether but common to all as you see.

ETA: The 10 m/s is nominal and you can use any value for that, even though there is a minimum speed at which no kite can "plane" (or fly). Try not to get side-tracked from the main issue. The Olympics have no place here. This is for science, not spork.

 

[humb]

Finally, someone is beginning to understand, and we're getting some sensible discussion in here. Of course the kite cannot fly properly when you are running, and yes, the laminar flow that you create in that case is reversed. This is why little kids always fail when they try this, they are too short and the kite cannot get to the nominal wind. Even then, if the kite gets to altitude and you then try to stand there at "windspeed", it will fall to the ground. It is the same if you tie your string to a treadmill and try to make it fly by running. The treadmill cannot generate its own wind in this way, because the flow will always be backwards. If you turn around, and turn the treadmill around, and turn the belt around, the signs will cancel, and it will still fail. Besides, the power cord is too short, and with the belt backwards your pants will fall down (not up). It cannot fly. A treadmill is not a kite.

 

[Ziggurat]

Also, if he can run 10 m/s, he should try out for the olympics.

I doubt I can do 10 m/s, but that won't get you into the olympics. Sprinters hit average speeds above that on the 100 meter, meaning their top speeds are significantly higher.

Of course, they're not dragging kites, but that's not an olympic event. Yet.

 

[Ziggurat]

A treadmill is not a kite.

Truer words were never spoken.

 

[John Freestone]

In case anyone is curious, here's the reasoning for why I chose 6 m/s as the speed of the air in the boundary layer (at some arbitrary distance from the surface). There had been some earlier posts that used 7 m/s for this value. I had thought about using 5 m/s, but I though there was some merit in not setting it at half-speed, so as to make clear which was the difference between this speed and the free stream flow, vs. this speed and the surface. And I made it 6 m/s so that the difference would be 4 m/s, and the time until the smoke puff went by would be 2.5 s, instead of the more unwieldy 3.33333 s.

So it's all your fault then! Just think how much more quickly this conundrum could have been "resolved" if you'd gone with 5. How would the universe have unfolded in that case?

Yes, when the numbers are close together it's always harder working these things out, especially by the method I use (close eyes, screw face up and wave arms about). Describing the gradient more fully throws its reversal completely. It's not so daft really to think that if the BL is going at 6 across the land, it will be dragged by the belt at 6 too. I could have got that wrong myself quite easily. But if you think of the bit that's so close to the ground (real ground!) that the air has been slowed to 1 m/s, you can't as easily think "it's obviously 1 m/s the other way when it's dragged by the belt", because somewhere way above that, the same simple reversal of sign would mean that the air is miraculously dragged by the belt at 9 m/s.

 

[John Freestone]

Sorry I interrupted your humberphysics discussion there for a moment. You know if you're too sarcastic, humber won't come back and fill in the missing windspeeds, and all my work trying to reach agreement with him will have been in vane.

 

[Clive]

Sorry I interrupted your humberphysics discussion there for a moment. You know if you're too sarcastic, humber won't come back and fill in the missing windspeeds, and all my work trying to reach agreement with him will have been in vane.

John, the multiple flaws in your diagram give you away. The master will tear you to shreds if you let him see those. For one thing the right hand panel shows the differential between air at head height and the belt below as 20 m/s. Attempting to fill in the missing values in those circumstances would be like playing Russian roulette. The direction of that differential isn't even specified. Meanwhile the diagram on the left has unexplained gaps. Perhaps your omission of 5 is as I explained to mender earlier. Is this meant to be a trap, the old good-cop, bad-cop routine? The laws of physics have a symmetry but 10 - 7 is undefined in your world? You will most likely be ignored for tastier targets.

I don't know why you mention sarcasm. To understand another you must stand in their shoes. Communication without understanding is futile. So is resistance. Join us now - the numbers are with us!