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

[spork]

Two identical cars approaching from opposite directions at equal speeds. When they pass, they will have zero velocity w.r.t each other, and zero KE.w.r.t each other For how long?
They are still running their engines at full power. Why?
Same for one car passing another. For how long does zero-land exist?
How fast would an object have to travel between those cars, to make use of that situation?

Honestly guys - does this not prove my point?

 

[mender]

Two identical cars approaching from opposite directions at equal speeds. When they pass, they will have zero velocity w.r.t each other, and zero KE.w.r.t each other For how long?
They are still running their engines at full power. Why?
Same for one car passing another. For how long does zero-land exist?
How fast would an object have to travel between those cars, to make use of that situation?

1) They never have zero velocity or zero KE wrt each other.
2) They are running their engines at full power because they want to go fast?
3) Zero-land; I guess I missed that post. Is it part of the Humberverse?
4) 74 ohms.

Now you have to answer my questions! Fair is fair!

 

[Christian Klippel]

Honestly guys - does this not prove my point?

Hello spork,

it does, indeed.

Wait until you see the humbermath. That will make your calculator explode!

Greetings,

Chris

 

[humber]

I was on a flight all day, so I missed several pages. Yes, that's how fast this cancer is growing. But in trying to catch up, I think some things are becoming clear to me. First off, I think it's far beyond hopeless to think we're going to achieve any sort of understanding with humber (and I suspect we all know this). The notion of this reaching any sort of conclusion that's satisfying to either side seems beyond remote. I'm honestly at a loss.

The more I think about this, the more I think we're "debating" someone we would avoid making eye contact with in person.

What on Earth do you mean by that, Spork? If you mean that I wouldn't look you in the eye, you are wrong, there.

I'm trying to figure out how to say what I mean without attacking the person, but I fear it's coming out wrong. I guess what I mean to say is that when we can only see what someone posts on an internet forum, we assume things that we'd never assume if we met the person face to face. Consider this model and ask yourself whether it's consistent with everything that appears here... this member literally doesn't percieve the world as you and I do.

I think you are right, when you say that we do not see things the same way.

I believe he has "experienced" some education, but I think it would be a mistake to call him "educated". I simply can't find a way to consolidate the combination of ignorance, arrogance, and persistence we see here, and ascribe it to someone that processes information like most other people do.

I don't know that anyone here has told me anything of significance that I did not already know, yet there are some who equate slower with "backwards", for example.
Perhaps a little less of the arrogance you just mentioned?

 

[humber]

Honestly guys - does this not prove my point?

No, this is what RossFW is suggesting. He equates a slower vehicle with one going backwards, in order to make the same case for flows. This is entirely false reasoning, as my questions show. No object can sustain zero KE, without permanently staying at the same velocity.

 

[mender]

Spork, I mostly agree but think that a one on one with humber would be much more fruitful than posting. I know that I would have understood relative wind in about 30 seconds (maybe less!) if you and I had been on opposite ends of a table with pens and napkins in hand. Humber can get away with saying as many incorrect things as he wants without fear of interruption. He can gloss over the important issues with "not relevant" or some other sidestep. Not so easy with someone watching each step.

I would love to have the opportunity to meet humbre in person. I would certainly find it interesting whatever the outcome! Ignarrosistant or not!

 

[Brian-M]

It does not need to overcome friction. For one thing, you tell me there is no force at windspeed, but then a cart balancing on a belt yet not moving, has no motion related friction to overcome.

I'm glad you finally do acknowledge that an object travelling at windspeed is experiencing no friction/drag from the air.

I am puzzled why you believe that the rapidly spinning wheels, gears, and propeller on the cart would not experience friction? After all, none of these things are travelling at windspeed, and they're also rubbing against each other too.

Do you think the propeller spins with 100% efficiency?
Do you think the wheels spin without friction on the belt and the 'bearings'?
Do you think the gears are frictionless too?

If not, then the cart has to overcome friction just to remain in place.
As spork has amply demonstrated, the cart not only manages to stay in place, but can gain momentum in the direction opposite to the direction of the belt.


ETA:

What a stupid comment.

Do you really want to tell us that there is a) no rolling friction, b) no friction in the bearing and c) no friction in the gears?

Really, humber, with such comments you make yourself the laughing stock here. But then, you are just that for the most of us already.

Edit: Oh, and lets not forget the losses at the prop. You know, that prop that generates the thrust to keep the cart in place.

Damn. Maybe I should try reading all the posts before responding.

 

[mender]

For one thing, you tell me there is no force at windspeed, but then a cart balancing on a belt yet not moving, has no motion related friction to overcome.

Careful, Brian-M, humbre tried to claim that having no unbalanced forces means that there are no forces present quite a while ago. Right after that, he switched to saying that one of us had been making that claim!

 

[spork]

What on Earth do you mean by that, Spork? If you mean that I wouldn't look you in the eye, you are wrong, there.

I posted exactly what I meant. You prove my point when you assume I meant exactly the opposite of what I posted.

I think you are right, when you say that we do not see things the same way.

I'm not speaking of you and I humber. I'm drawing a distinction between you and those that enjoy relatively normal mental health.

Spork, I mostly agree but think that a one on one with humber would be much more fruitful than posting.

I optimistically thought that as well, even quite recently. I suggested to humber that he and I have a conversation via Skype. He declined with a bizarre excuse about moving between several different computers. Of course the notion that someone that spends hours each day on this thread can't spend 10 minutes on a Skype conversation to determine whether there could possibly be any common ground, is just as ludicrous as the possibility that he understands physics but is the only one unwilling to answer some basic questions.

I now think if we each had the benefit of a one-on-one with humber, we would have walked away from this long ago. I suspect we'd realize this is beyond hopeless, and probably feel at least remotely sad for him.

I know that I would have understood relative wind in about 30 seconds (maybe less!) if you and I had been on opposite ends of a table with pens and napkins in hand.

There's no question that face to face is usually FAR more effective, but again I think that presumes a certain commonality to begin with. It presumes both parties are willing and able to apply logic, both are at least capable of discussing the topic at least at a very basic level, and both are interested in coming to a common and accurate understanding. I don't think any of these things are true for humber.

 

[RossFW]

I'm sure I'm not the only one getting a guilty pleasure out of this. I think we are all beyond hoping Humber will admit his errors and basic mis-conceptions and are just throwing out questions to see exactly how dumb his answers will be -I know I have (Identify the Python reference!!)

I don't think it's beyond the pale, therefore, to see if we can't infer a little about the mind that is the Humber form the data we have.

First up, we are not talking about someone with an extensive education. I can't believe that anyone with any higher learning, even if it were in non-technical fields, would lack the simple abilities at mental modeling and VERY basic physics to be able to make such fundamental errors.

Secondly, he knows a lot of big words and ALMOST knows what SOME of them mean (He didn't ask for some Adiabatic on his Burger, he knew it had SOMETHING to do with air). He thinks if he bandies them about, it infers knowledge (e.g, when I asked a simple question about True Airspeed vs Ground Speed he through out Mach No. (For the record, we were talking about 100mph- so about M0.13 at sea level- you don't find Tiger Moths with compressibility problems!!) but drops them quickly enough when asked to explain their relevance.

Thirdly, from his writing I would assume that English is not his first language. There is a certain brusqueness and syntax that suggest to me a language background in one of the harsher sounding ones.

I have lived in a few different parts of the world and travel globally. If there is one thing I have learned it is that, PC or no PC, there ARE cultural norms that shape behavior and attitudes in people from different places.

In many cultures, it is VERY hard for people, particularly Males, to admit error or even lack of knowledge of a subject. Culture is a well documented factor in many air accidents where a proud pilot, culturally pre-disposed to not admitting error, will press on with an eventually disastrous course of action rather than admit error, and with those around him remaining silent so as not to "dis-honour him" by saving their own lives!!

These people react VERY badly when error is pointed out to them (I used to fly in Japan, and have some first hand experience of this!!)

So my read on this?

Humber is a rudimentally educated person, later trained in a technical trade (I'm thinking electrician) with a keen interest in Physics, but without the basic grounding to comprehend basic concepts. He is originally from a hierarchical, male dominated culture, and is not used to those around him contradicting or correcting him (Plus, I don't think he HAS many people around him!) and gets very cross when anyone does.

Any thoughts?

 

[Brian-M]

Indeed. And now, what exactly makes that rock a mechanical structure, so that you could compare it to mechanical impedance?

Maybe he's referring to the mechanical imedance of the water, which from it's own inertial frame is being pushed by the rock?

 

[humber]

But you've gave the belt velocity as 10m/s in that post and the "flow" as being -6m/s... so according to your numbers, they're moving in opposite directions.
Can I assume that you left out the negative sign in front of the 10m/s by accident? And also left out the negative signs in front to your answers by accident too?

I think it is best not to assume anything, Brian-M...

You can't just leave out the negative signs on half your negative numbers and still expect your math to make any sense to anyone else.

Mmm...

Here, let's start again with a wind-speed cart.
On The Road
Measured from the ground - Beside the road.
Boundary layer (at height X) is 4m/s slower than the wind.

Wind = 10m/s
Cart = Wind = 10m/s
Boundary Layer = Wind - 4m/s = 6m/s
Road = 0

OK, so far, so good.
Now make the "wind" bit zero. The flow moves forward at the nominal 6m/s.

To measure from the cart's perspective (or wind's perspective, which is the same thing as they are moving at the same velocity), subtract the cart's velocity (10m/s) from everything.

Wind = 10m/s - 10m/s = 0
Cart = 10m/s - 10m/s = 0
Boundary Layer = 6m/s -10m/s = -4m/s
Road = 0 - 10m/s = -10m/s

Instead, add the wind.
Wind = 10m/s
Boundary = 6m/s.
The cart will be at 10m/s.

You can say 4 things. I think
(1)The Wind is faster than the boundary by 4m/s
(2)The Boundary is slower than the wind by 4m/s
(3)The Boundary is going backwards by 4m/s w.r.t the cart
(4) The difference ( Wind - Boundary) is 4m/s

Now we try it on the treadmill
On The Treadmill
Measured from the ground - beside the treadmill
The boundary layer (at height Y) is still 4m/s slower than the wind.

Wind = 0
Cart = 0
Boundary Layer = Wind - 4m/s = -4m/s
Belt = -10m/s

No. The belt speed is the windspeed so, that is -10m/s. The flow is 4m/s, slower, and so -6m/s. As you would expect, 6m/s in the opposite direction. I suppose if you can "make the belt speed zero", the boundary will move along the belt at 6m/s.
It is exactly like the wind, but going the other way, its profile is the same "shape", but the fastest bit is actually at the road, going to zero at the wind. So it must be -6m/s.
However, the profile is not linear, so 6m/s will not be at the same depth in each case. Closer to the wind in the real case, but closer to the belt on the treadmill.

Wait a sec... That's EXACTLY the same as on the road, from the cart's perspective!
Let's look at it from the belt's perspective by subtracting belt-speed from everything.

Wind = 0 - (-10m/s) = 10m/s
Cart = 0 - (-10m/s) = 10m/s
Boundary Layer = -4m/s - (-10m/s) - 6m/s
Belt = -10m/s - (-10m/s) = 0

Exactly the same as we start with on the road!

There is no difference.

Not if the answer at windspeed is -6m/s

This is a trap I think. The paddle averages the forces if you will, so you can just assign a nominal value to the depth of the flow.
You are still ignoring the fact that the observer-generated wind and boundary flow pass that observer, up the belt, whereas the belt-boundary travels in the opposite direction. The paddle detects this too.

ETA:I imagine that the belt boundary is a thin layer of fog. Sit on the belt, but ignore the wind from behind. Part of you is travelling with the belt, but part is at zero wind. So for the -6m/s wind, you should see a flow, 4m/s going up the belt, backwards to you. This is like "winspeed" for the cart in real wind, (Option 3) but w.r.t to you.
But, there will be a wind of 10m/s from the rear, that makes, 6m/s down, 10m/s up, which is the same as the 4m/s 'backwards' up the belt +4m/s. At windspeed it is 6m/s down the belt, or -6m/s. or -4m/s if you take your view. Again, the paddle shows this.

 

[Brian-M]

Hey, humbre, speaking of space, two spaceships are out in space and they are at rest with each other and are pointing in the same direction. One of them fires their thrusters and starts to move. Who is moving backwards? Who gets to decide?

We went over this one in the original DDWFTTW thread, so I can confidently predict that his answer will be something along the lines of:

It's the history of the object that's important.

 

[spacediver]

interesting analysis ross.

I'd love for humber to post a youtube video of himself discussing something. It may shed some light on his character.

I'm not one who likes to categorize people into mental disorders, but there is something to be said about dysfunctional patterns of reasoning that emerge in similar forms across different minds.

Whether this be the conspiracy nut, the paranoid schizophrenic, and arguably even religious people, you see these same patterns.

I would love to have a 1on1 session with humber where I could intervene in his thought processes at high resolution. I could ask him to solve a high school physics question and watch him as he does it on a piece of paper, squirrels mating nearby...

Humber, where do you live?

 

[Brian-M]

No. The belt speed is the windspeed so, that is -10m/s. The flow is 4m/s, slower, and so -6m/s.

From the perspective of someone standing on the belt... Belt = 0m/s Wind = 10m/s From this perspective, belt-speed is not wind speed. From the perspective of someone standing beside the treadmill. Belt = -10m/s Wind = 0m/s From this perspective, belt speed is not wind speed. Belt speed is not wind speed no matter which way you look at it. If you want to add up the figures, you have to add up the figures from the same perspective inertial frame. Mixing them up like you do results in gibberish.

 

[H'ethetheth]

I imagine you would. So according to you, a self-powered fish, in motion, in water, is like a cart driven from the wheels, but with no motion, in still air? Perfect match.

My point about wind tunnels, humber, is that the cart on the belt is simply a special case of a windtunnel experiment. Namely where the wind in the wind tunnel is zero. If you work with wind tunnels on a regular basis, you are almost always putting yourself into the shoes of a reference frame that is hard to reach. That is the whole point of wind tunnels.
The benefit of this, is that you become familiar with imagining the world from all kinds of moving reference frames; something that you are manifestly not good at.

That is not the point and arguable. I can control the flow as I wish. That is only a matter of technology. I could use other many other methods. An array of MMIC's perhaps.
The headwind from the fan would combine as expected. In fact, there is no reason why I could not pre-condition that as well.

No, as long as you keep the car horizontal, you can never recreate a horizontal boundary layer by indroducing vertical flow. No technology or methods will change this. You introduce vertical mass transport that has no counter part.

Belts induce harmonic motion into the flow, so they do have side effects.
Motion of the belt is not necessary to the creation of the boundary conditions under the car, so there can be no implied motion for the car. That is the point.

That is true, but it is by far the somplest way of creating a perfectly valid model.

The belt is used to imply motion on the treadmill. That is false.

The belt moves. That is motion. From the car, it's just like always: a surface moves by from front to back; that's all there's to it.

Self-contradictory. Not unlike yourself.
I mentioned your personal appeal to authority on our first encounter. You have done it again, and with no justification.

No justification? You are not educated in the field, demonstrably wrong, and fail to acknowledge that. What not to justlfy?

I do not see that you have met your other claim that your knowledge of relative velocities or equivalence affords you expert status. In fact, the offering is about as far wrong as it is possible to be, and not original.

I would feel hurt if I thought you knew what you are talking about,
-----------------

Now we have that out of the way, perhaps you would like to tell me how Bainbridge's device is comparable with the treadmill, as you claimed you could in #1738. Two similarities, with exemptions do not make for "equivalency".
You may chose another device if you like.

I'm going to tell you, but you will fail to acknowledge that it has anything to do with it. I know that it is not an equivalent to the cart on a treadmill, in case you're wondering, but it has a lot in common.
Let me ask you a question: Is the fish wheel designed to model fish swimming upstream?

 

[Brian-M]

Let's Take Some Tests!

I've found some physics tests on the internet that we can try.

Intuitor Physics Savvy Quiz

High School Certificate - Physics Exam Questions


The first one is really good, if somewhat tricky. I managed to get 87.5%, even though when I looked over my mistakes I discovered I'd accidently marked one box false when I meant true, and I discovered I had misread one of the other questions.

The second one is put out by the New South Wales board of studies, which generates a random quiz using real exam questions from previous exams for self testing purposes. It's not a full exam, or even close to being a full exam, just 15 multple choice questions. I don't think we can use this one as a standard, because everyone will get different questions, but it's a good challenge.

I went to High School in New South Wales (that's not why I picked the quiz, Google just happened to bring it up), and I'm not sure if the questions have gotten harder or if I've forgotten too much. I still managed to get 73.3%, which is better than I did in the full exam 13 years ago.

So if anyone wants to have a go, be my guest.

And if anyone can figure out how to get Humber to take them and accurately report his results, I can't wait to hear it.

 

[RossFW]

This has been the fundamental error all along, Brian.

What he is saying is that someone in the (to Humber!!) privileged frame of the earths surface can see the belt moving at 10m/s, and can also tell the person on the belt will feel a wind at 10m/s.

He believes you can do calculations wrt your frame of reference using figures you infer about someone Else's.

When he says "The cart has zero KE in all frames" he means anyone in any frame can see the cart has zero KE wrt the ground, and he thinks that makes his statement true.

If ONLY he got the very basic idea of there being no privileged frame of reference, it might all slip into the Humber brain (NO BUT I CHOOSE THE EARTH AS MY REFERENCE, SO IT IS SO!!).

But I'm not holding my breath.......

 

[humber]

We went over this one in the original DDWFTTW thread, so I can confidently predict that his answer will be something along the lines of:

It's the history of the object that's important.

That's easy. The one with with the booster will be accelerated, so that is the one that is moving.
Backwards is jut an illusion of the observer.That's too complicated to explain, but there is another way.
The acceleration history is not recorded by the instrument, but by the object itself. It has to be somewhere, at some velocity, and that history puts it where it is.
It's a chain that is the sum of all the things that have ever happened to it.
The accelerometer can tell the human operator what is happening now, thing 'next' thing in the chain, but mostly, objects don't care.
I don't know why you worry so much about where things "really" are.

 

[Subduction Zone]

Well I got 95% on the first test but it is late at night for me and the second test was straining my brain a bit, so I humbered it, ie I gave up and gave myself an A+