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

[humber]

If Stephen Hawking were to roll his little wheelchair up to humber's front door and tell him that, having read this entire thread, he felt compelled to announce that the operation of the cart on the treadmill is exactly the same as on the road, that this is a perfect way to test a DDWFTTW cart, that DDWFTTW works, and that the treadmill videos are incontrovertible proof of this, then humber would immediately turn to us and say,
"See? Hawking supports me completely! The treadmill is completely wrong, and backwards!".

Tertiary education? How embarrassing for you.

 

[humber]

Just in case you were serious about that (in a thread full of so much garbage it's hard to be sure), that's not true. Galilean relativity says that inertial frames are equivalent - but orbiting objects are accelerating.

Today's nanofact.

 

[humber]

The moon does not define an inertial frame, since it is (like the earth) accelerating. For experiments with the DDWFTTW cart, a region at the surface of the earth can be considered to be an inertial frame, since the acceleration of the earth is so slight that it won't make any difference at the level of accuracy required for such experiments.

Consider the lily. Yes, too far away to be of interest. Swamped by almost anything. Assume conditions to be local. Set watch to moon time just in case.

When analysing the orbit of the moon around the earth, it's best to consider moon and earth as a pair of bodies rotating around a common centre of mass.

Phew!. Now solve the three body problem, N-body by lunch.

 

[spork]

Does this remind anyone else of the ramblings of the HAL 9000 as it was going down?

I expect humber to start singing "Daisy" within the next couple of posts.

 

[humber]

Does this remind anyone else of the ramblings of the HAL 9000 as it was going down?

More like The Titanic.

I expect humber to start singing "Daisy" within the next couple of posts.

Not to be missed.

 

[spacediver]

Humber, I paid a hobo to get in a car and toss things around - here's the video:

http://video.google.com/videoplay?docid=5045171464168585988&ei=Y9FsSdieDJ-2-wGZ7JnnDA

 

[CORed]

Of course, it seems humber is good at this, and knows how to press our buttons. He dodges difficult questions by someone who is losing their will to live, and focuses on someone returning after a little break. Collectively, we're just here supporting him in whatever it is he's doing - digging a deeper hole for himself, or getting the attention he craves, or making him feel that he might possibly still be right, or crossing off another day on the calendar that he's suckered us in.

I've gone back and forth on what humber's motivation might be. On one hand, it seems unlikely that anybody could be as consistently wrong on simple things as he is, unless he's just messing with us, on the other hand, he is remarkably persistent for somebody who is just playing games. I have found myself starting to post several time lately, and saying to heck with it, I've been over this ground before, and I don't like to repeat myself endlessly in a thread. Then he will post something so ridiculous that I can't help myself.

 

[humber]

Humber, I paid a hobo to get in a car and toss things around - here's the video:

http://video.google.com/videoplay?docid=5045171464168585988&ei=Y9FsSdieDJ-2-wGZ7JnnDA

I hope you paid him well. He's going to need the money to pay for those speeding tickets he is likely get for traveling faster than the Milky Way.

Next week: The secret of fire.

 

[humber]

What amazes me is how much my feelings change, and with them I change my mind...

We all feel like that from time to time. I have you tried new Relativit-ease?

I also use it like CORed, for entertainment..

Whatever can that mean.

Dan O seems to have managed to stay off the thread for a while.

He was managed off, yes.

 

[CORed]

Does this remind anyone else of the ramblings of the HAL 9000 as it was going down?

I expect humber to start singing "Daisy" within the next couple of posts.

More like Nomad on the old Star Trek episode after he realized he'd made a mistake. If that's the case, keep your distance, he's going to explode.

 

[H'ethetheth]

Yes, H'ethetheth. The boundary layer(s) is/are going the wrong way.

No.

 

[Clive]

Humber, let's forget spork and JB's treadmill for now. I've been re-reading your earlier post to me (referenced below), and wondering if perhaps a slightly different approach will help shed some light on the matter - assuming of course you are willing to give things another whirl!?

Take the F1/BMW wind tunnel. This is a correct model, that uses real wind. The car is also artificially stabilized.

Imagine that you have access to the F1/BMW tunnel that you have referred to several times now, and you also have access to one of spork and JB's carts. You wish to simulate the cart running downwind at exactly the speed of the wind, when the speed of the wind over the ground is 10 mph. The cart will be held in a fixed position relative to the tunnel as a whole (as per the car in F1/BMW online videos). I realise this is probably a long way out of the design range for the tunnel and measuring equipment but we can pretend that BMW have tweaked that for you also.

Relative to the cart, what speed and direction will you run the belt at, and what speed and direction will you blow air through the tunnel if you want to measure the net force on the cart in that situation?

If you can see that the configuration you give is unlikely to allow correct measurement of some particular aspect for some reason, can you please try to explain what you think those problem areas might be, and why, and if there is any solution in your opinion?

 

[Brian-M]

The first sentence is incorrect as written. A corrected version could be: "If they wanted to simulate driving at 300km/h in a 300km/h tailwind, they wouldn't need to use the fan, but if the wind was from any other direction or at a different speed then they would have to."

You're right... I think I've been conversing with Humber for so long that I too am beginning to leave out vital keywords from my sentences.

Perhaps I'm just not quite getting what you've said in the last sentence but I would replace that with something like: "The fan is there to generate the correct apparent wind felt by the car given the particular details of the real world situation being modelled." Alternatively, "The fan produces a wind relative to the moving belt that simulates the weather related wind (relative to the road) in the real world scenario."

What I was getting at is when driving on the road on a day with no wind, there is zero relative velocity between the air and the road. So, to simulate driving on a windless day on a treadmill, you need zero relative velocity between the air and the treadmill, which is achieved by the fan blowing the air at the same speed as the treadmill belt is moving.

In other words, when driving at 300km/h you have a 300km/h headwind. To simulate this on a treadmill, you need to use a fan to create that 300km/h headwind.

 

[Brian-M]

Just a minor correction. Where you say "laminar flow" you should say "boundary layer". Laminar flow is simply the opposite of turbulent flow.
I say this mostly to be pedantic, but also because the boundary layers we are discussing here are decidedly not laminar.
I'm not sure if who made the mistake first, but it would help if we're all discussing the same things.

Thanks for that. I just saw the expression used on this thread and deduced what it was referring to from the context of the posts, and simply assumed it was the correct term. Silly of me really, considering that Humber is involved.

 

[Brian-M]

I see us all doing it, changing our minds. Dan O seems to have managed to stay off the thread for a while. There's hope for me yet. But I remember him once asking everyone to stop feeding the trolls, in the same thread as asking humber to provide test details. To him I'm sure that made sense - if that were just pressed forward with no distractions, humber could be shown to be wrong. Since then he said he was stopping or putting humber on ignore several times, IIRC.

I know what you mean. I'm on the verge of giving up on him (again).
I'm not sure that "troll" is the right word here. I tend to think of him as a bit more like "Smeagol" than anything else.

 

[spork]

Humber, let's forget spork and JB's treadmill for now. I've been re-reading your earlier post to me (referenced below), and wondering if perhaps a slightly different approach will help shed some light on the matter - assuming of course you are willing to give things another whirl!?

Please tell me you're just messing with humber - or us. I don't think I can watch anyone actually try and talk sense into humber at this point. But I can't look away either. It's a friggin' train-wreck. Please tell me you're just tapping on the glass.

 

[Clive]

What I was getting at is when driving on the road on a day with no wind, there is zero relative velocity between the air and the road. So, to simulate driving on a windless day on a treadmill, you need zero relative velocity between the air and the treadmill, which is achieved by the fan blowing the air at the same speed as the treadmill belt is moving.

Thanks. I was probably thrown by you saying the purpose of the fan was to cancel out the apparent wind. To me we need to create the apparent wind, because in the treadmill with no fan we have no apparent wind. Anyway, I'm confident we're in total agreement on the essential details even if we're possibly trying to use the same words in slightly different way!

 

[Brian-M]

You are confusing motion through airflow, with the flow. The laminar flow moves with the wind. The difference between the wind and flow is a constant 3mph. When you add speed to the windblown object, you add speed to the hand.

But the hand is moving 2mph slower than the wind, while the laminar flow boundary layer is moving 3mph slower than the wind.

The hand is clearly moving faster than the laminar flow boundary layer. Can't you even do basic addition and subtraction?

Since the hand is moving is moving 1mph faster than the laminar flow boundary layer, that means the laminar flow boundary layer is blowing backwards against the hand.

Exactly the same as what happens on the treadmill. Your hand test is a complete failure.

Real wind can move an object independently of friction to the road.

No it can't. Real wind can't move an object unless the force applied by the wind is strong enough to overcome the objects friction with the road.

Unless you mean that in a real wind, an object with little or no friction to the ground will be accelerated until it's velocity approaches windspeed?

If so, the same thing applies on a treadmill. In the apparent wind, an object with little or no friction to the belt will be accelerated until it's velocity approaches apparent windspeed.

It's exactly the same thing.

That the real wind, is a source of power that blows over the road, is not a matter of convention.

Yes it is. Unless you're claiming that all of physics is wrong and that velocity is an absolute after all?

The belt is just a source of power. What of a car on the a road? If you put a real car on a running belt, but do not start the engine, do you think that is the same as a car on the road?

Yes, I do. A car parked on a moving belt is exactly the same as a car parked on the road in the wind.

In the real world, the wind drives the propeller directly, exchanging real energy and the load of the cart as it is propelled forward. The belt can only drive the propeller, via the friction too the belt. That limits the power doesn't it? To that force too is determined by gravity and friction, and to low to drive the cart, or only just a bit.

Edited by Gaspode: 

Edited for rule 10. Do not attempt to bypass the auto-censor

How many times did we explain this to you in the old thread? I even made up a couple of animated carts, and provided mathamatical explainations, as did others.

Remember: THE WIND DOES NOT DRIVE THE PROPELLER!

The gearing is all wrong for this. The wind does not have enough leverage to turn the propeller, and if it did this would make the cart run backwards, turing it into a Direct Upwind cart.

The propeller turns the opposite direction to how the wind is pushing it. The propeller drives the cart forwards by pushing against the wind.

As the cart moves forwards over the surface, the surface turns the wheels, which in turn drives the propeller. Friction from the belt, friction from the road... both these things are exactly the same. It doesn't matter if the cart is on the road or on the belt, the relative motion from the surface it is moving over drives the propeller by turning the wheels.

I can't believe that after all this, you still don't understand even the basics of the cart.

 

[H'ethetheth]

Humber, let's forget spork and JB's treadmill for now. I've been re-reading your earlier post to me (referenced below), and wondering if perhaps a slightly different approach will help shed some light on the matter - assuming of course you are willing to give things another whirl!?



Imagine that you have access to the F1/BMW tunnel that you have referred to several times now, and you also have access to one of spork and JB's carts. You wish to simulate the cart running downwind at exactly the speed of the wind, when the speed of the wind over the ground is 10 mph. The cart will be held in a fixed position relative to the tunnel as a whole (as per the car in F1/BMW online videos). I realise this is probably a long way out of the design range for the tunnel and measuring equipment but we can pretend that BMW have tweaked that for you also.

Relative to the cart, what speed and direction will you run the belt at, and what speed and direction will you blow air through the tunnel if you want to measure the net force on the cart in that situation?

If you can see that the configuration you give is unlikely to allow correct measurement of some particular aspect for some reason, can you please try to explain what you think those problem areas might be, and why, and if there is any solution in your opinion?

It's a good question, but not a new angle. But then again, he never directly answered this question when I asked it. Maybe you have more luck.

 

[Clive]

Please tell me you're just messing with humber - or us. I don't think I can watch anyone actually try and talk sense into humber at this point. But I can't look away either. It's a friggin' train-wreck. Please tell me you're just tapping on the glass.

Well........ I'm not really sure exactly what I'm doing (or why), but certainly not messing with anybody. Let's just say I have lots of spare time at the moment! If humber is willing to respond in a way that at least approximates something intelligible and to the point, then I'll attempt to respond in kind. Tapping on the glass... yes... that's pretty close! You just never know... there's always an outside chance! Can you hear me humber?