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

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This has been the fundamental error all along, Brian.

Oooh, good, gossip.

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.

When will you stop telling m what I think, RossFW? No, I do not think that.
I say that the view from the ground is not privileged, that's a human value, but exactly the same as any other, so I have no reason not to choose it.

However, it is rather convenient because that is where gravity likes to put things. To move from this spot would result in the same information; all that you can ever know about those objects, but will make it difficult for you, not perhaps mathematically, but it will be at complete odds with your evolved senses and learning concerning that behavior. Why bother, when there can be no benefit, and equivalence says there cannot be.
What he also says, is that it is possible to tell those views apart on the treadmill. Equivalence allows you to swap your view from wind to ground but not to swap the wind for the road, or keep a moving object in stasis. That is quite something else all together.

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

Burn him at the stake.

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.

I don't think that makes sense to even you, RossFW. He says if it has zero KE w.r.t the ground, it won't be moving w.r.t he ground; in linear motion at least. That also quite conveniently means nowhere else of concern to you, or any one actually on the ground. You say this is not so.

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.......

Good words and true.

No, you wouldn't be asking easily shot-down questions about balloons and relative car velocities, as is if you were talking to the village idiot.
Nor would you be assiduously avoiding answering all those questions about how the cart's KE finds its way to the belt, without any known mechanism.
Many others, too.
 
Folks, i have to repeat this humber-statement, because it is really telling:



Get that, dudes! And that comes from someone who claims to have superior knowledge of physics compared to us.

Bull as bull can be.

Objects have their own guardian angels to make sure they never get lost, Christian. You know, causation?
 
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've just done the first one and got 85%. There are almost two tests going on at the same time. Firstly your ability to understand how "deep to go" when interpreting the question (so that you answer it at the "right level" if you see what I mean) and then your actual knowledge. Out of my six errors I think I'd class about 3 of them as being in the first category. But even when I look at the other 3 there's nothing there I didn't actually "know". So I should really have got 100%! :)

ETA: #29 was one that I got wrong Christian. What is the exact definition of one of "those things" anyway? (I'm trying not to give away to many clues by mentioning the specific details) So I was thinking about that too much and ended up actually making the mistake that nearly caught you out. :(
 
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Hello Clive,

I've just done the first one and got 85%. There are almost two tests going on at the same time. Firstly your ability to understand how "deep to go" when interpreting the question (so that you answer it at the "right level" if you see what I mean) and then your actual knowledge. Out of my six errors I think I'd class about 3 of them as being in the first category. But even when I look at the other 3 there's nothing there I didn't actually "know". So I should really have got 100%! :)

yes, some of the questions have a rather tricky phrasing. But makes them even more funny, i think. A few of them have some kind of morbid humor in them.


ETA: #29 was one that I got wrong Christian. What is the exact definition of one of "those things" anyway? (I'm trying not to give away to many clues by mentioning the specific details) So I was thinking about that too much and ended up actually making the mistake that nearly caught you out. :(

Well, one of these things is when you heat water up to a certain level at least, the other is when that stuff cools down after it was heated up that much. Hope that didn't gave away too much.

Greetings,

Chris
 
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Well, one of these things is when you heat water up to a certain level at least, the other is when that stuff cools down after it was heated up that much. Hope that didn't gave away too much.
Ah, yes... two separate things... I was distracted by thoughts of the "medium" in which the cooled thing was "suspended" and if that medium was actually part of the bigger thing or not! :D
 
Question 15 really makes no sense because a vector has no sign. The explanation is even worse because it still talk about a sign of the vector. The only possibly definition (that I can think about now) of the sign of the vector involved (using the angle) also implies that the answer is wrong.

It is not strange that some misconceptions exist when explanations that is supposed to get rid of the misconception include a couple of new ones, undefined terms etc.

It is not much better (maybe worse) if only 1d is considered (I believe they actually do this in the explanation) because it make no sense to talk about positive velocity or acceleration in an absolute manner only because the coordinate system chosen gives a negative sign.
 
Question 15 really makes no sense because a vector has no sign. The explanation is even worse because it still talk about a sign of the vector. The only possibly definition (that I can think about now) of the sign of the vector involved (using the angle) also implies that the answer is wrong.

It is not strange that some misconceptions exist when explanations that is supposed to get rid of the misconception include a couple of new ones, undefined terms etc.

It is not much better (maybe worse) if only 1d is considered (I believe they actually do this in the explanation) because it make no sense to talk about positive velocity or acceleration in an absolute manner only because the coordinate system chosen gives a negative sign.
Yeah. 15 was another of my X's! I sat there thinking about vectors for a bit. Shouldn't have got that one wrong but had some kind of brain fart when I switched to 1d and was far too unimaginative with a possible scenario they could have been thinking of. Humber would probably improve on my effort with #23 also. And then there is #17 (which I managed to get "right") even though the other choice is definitely "truly correct" in my opinion!

ETA: Maybe we need to have a competition now to find the "most incorrect correct answer"? :D
 
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I've found some physics tests on the internet that we can try.

Intuitor Physics Savvy Quiz

Your Total Score is 95 %

I'm happy with that.

Question 15 really makes no sense because a vector has no sign. The explanation is even worse because it still talk about a sign of the vector. The only possibly definition (that I can think about now) of the sign of the vector involved (using the angle) also implies that the answer is wrong.

You're right. I assumed 1 dimension and got the right answer, but the question could be better worded.
 
I'm glad you finally do acknowledge that an object travelling at windspeed is experiencing no friction/drag from the air.
I meant that internal friction. The small amount that is required to for it to spin, and stay in place. Not an real work of motion.

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.
Yes, but only that is only a small amount of work, internal losses.

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?
No,no,no.

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.
No, that is simply a matter of stability. If the prop were driving the cart, it would definitely move forward w.r.t the belt, that (unavoidably) generates motion w.r.t the ground. That small motion you see, is that motion w.r.t the ground. That is some real work, but it is small, and largely 'drift', the result of variation in the friction, but I think the the momentum of the prop. ensures that drift is mostly in the direction of the cart. It takes little work to stay there, in principle,, nothing.

ETA:

Damn. Maybe I should try reading all the posts before responding. :)[/QUOTE]
 
Humber, did you miss sporks and ynots videos when the cart moves forward relative to the ground with a good speed?
 
87.5 on the first one. My electrical knowledge sucks. I dis-agree with No.22- The ball DOES have an accelleration in the upward direction, but with a negative magnitude- as someone said, you had to not look too deepley.

I'll try the second one soon....
 
Good Sometime*, Gentlepeople**

How are things today at humbre's ashram of advanced mechanics, I wonder.

(*well, it's afternoon to me, **and I don't know your sex, although I think that most 'girls' have better things to do than argue about their toys!)

Lets see how Humber refutes this analogy (I'll even take him off ignore, temporarily):-
I just love to say "I told you so". Great answer the Master gave, wasn't it?

See, I was right, humbre always takes the ground's point of view as the only valid one. He just can't understand how anyone could think differently.:jaw-dropp

Everything has the common reference of the ground, unless you're out in space, in which case gravity no longer attracts the mass that becomes the weight to provide the friction to supply the force which can't accelerate the cart, so the treadmill is invalid.
Yes, or any train of linguistic doodling that ends up "so the treadmill is invalid". That last paragraph is ace - there's an alternative children's nursery rhyme in there if anyone's got a cruel streak and hates their kids enough. It might need tweaking a bit, but you're definitely onto one. You know the kind of thing: the first verse starts off with a short statement that ends up "so the treadmill is invalid", and then each round works backwards, adding another line, like The Twelve Days of Christmas, or There Was an Old Woman (who swallowed a fly...).

Cool. I got a tick from Humber! I will treasure this. Is there a T-shirt I can buy? :)
Yes, but you have to put it on backwards.

<snip>

SOS SOS SOS ... what the hell am I doing here!
I know!...?

Regarding that question of what humber is doing, and what we're doing, I agree that it's a mix of being wrong, trying to cover his wrongness, not understanding why he's wrong, having learned some of why he's wrong, having a very narcisistic personality, delusions, poor education, etc., and one big thing that's missing (although covered by the personality disorder details if one looks at DSM) is pure unadulterated jealousy.

One principle in my therapy training that's useful is that at some level, we never really grow up. Our games are still very like those of children. Someone's got a cool toy cart (Spork & Co, as humber calls them), and everyone on the street is amazed and can't believe it does the virtually useless fun thing it does, but they eventually come round to seeing that it does do that, learning a lot of physics in the meantime, while humber stands on the street corner shouting abuse.

It doesn't do what Spork & Co says it does, because he didn't invent it, hasn't got one, can't be bothered to build one, and couldn't get his head round the physics on the first day. Thereafter, he just comes out to watch it NOT go. Now we're probably all enjoying the war games much more, and the cart is just there, slightly neglected, as a symbol of our feud.

Over the weeks we tried to explain how the toy works by reference to other well-known ones, but he just shouted across the street that if we had a hot-air balloon, or a train, or a boat, or a ball, or a gun and bullets, or an elevator, or a treadmill, or a moving walkway, or a rocket, or a fishtank, or any fish, or a propeller, or a flywheel, or a wheel...(not a complete list, I'm sure)...or any other toys, they wouldn't do what they're supposed to do either.

We didn't listen properly when our teachers (Galileo, Newton, etc.) tried to explain things to us. He's read them in the original Hebrew, and knows what the true message was. We didn't listen at school. Our dads are rubbish. Etc. Then we go in for tea.

But this thread isn't supposed to be about personality disorders, humber or carts.:)
 
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Besides the entertainment factor, this thread does have some value. Every time you all futilely try to explain the same basic concepts to Humber, lurking physics ignoramuses like me learn something.

Keep it up!
 
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.
But which reference frame,H'ethetheth? Do you say that the belt implies motion for the car, and/or is that is true only from the belt?
That the car can be actually said to be traveling in some way?

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.

The air under the cart comes mainly from the fan, the belt modifies that, or perhaps it can be considered as the supposition of the belt-generated flow, and that coming from the fan.
I did not say the array produced vertical jets; it can be directed. There are grid patterns that could even 'focus' the array.
If I had another set in front of a car that is going into the headwind, I could pre-condition that coming 'boundary layer', to make up for possible limitations of the set under the car. This system has some advantages because it is prescient, allowing the system to 'anticipate' the future and so gain better control. Perhaps it could even mimic braking or cornering down force by changing the pattern under the car in real-time.

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

I did say that. That it was a matter of convenience and cost. Belts work, but it is not the only way, so the same tunnel could be built without a belt. The wheels may spin or not.

No justification? You are not educated in the field, demonstrably wrong, and fail to acknowledge that. What not to justlfy?
I would feel hurt if I thought you knew what you are talking about,

OK, please, forget about that then, H'ethetheth.
-----------------
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?

The differences are paramount. If you consider the treadmill, the only independently active component is the belt.

There are several possibilities for the fish tank. I think the most likely is that the fish swims in contra-rotation to the water channel. One gate act as a paddle and the other opens so the fish can pass, and this process generates a flow over the fish so it swims against it (upstream). The camera can track the fish by operator (feedback) control. Flow could be controlled by partially opening the gates.

On the other hand the channel could go with the fish, so stimulating it forward.

The most banal is that the fish swims in still water (w.r.t itself), and the device rotates in the opposite direction so it can be filmed. It's rather like a stroboscope in that case.

This differences greatly from the treadmill.
(1) The fish is independently self-powered. (Cart via the belt/wheels)
(2) There is flow of the medium, either generated by the paddles or the travel of the fish through it. (Only when the cart travels with the belt)
(3) There is motion. (No significant cart motion expected of the implied speed.)
(4) The fish does work ( No apparent cart work)

These differences are paramount. A car driven by it's own engine is in a different class from that driven by the belt, for example.

The point I am seeking, H'ethetheth, is that the treadmill has taken the process too far by removal of the wind, and so only bears comparison on that basis. This rules out Bainbridge's device.
You seem to disagree upon the basis of the belt implies motion, or relative motion.
(BMW using the car and belt without wind)
I raised the 'static boundary layer generator' to show that belt motion was not necessary to the effect, and it would be hard to argue at all for motion (or equivalent motion ) without that belt motion.
Furthermore, in the BMW case I think the correct boundary will not be reproduced unless the wind coming under the car from the fan is included.
 
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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?
The full spectrum from WRONG to MEANINGLESS. Humber, just go to school first, (sell your computer if you have to, to pay for it) then, when you've got an education, buy a computer, log on and start talking to other people.

Those cars approaching each other - their velocity w.r.t. each other is the sum of each of their separate velocities w.r.t. the ground. Crash at 60 mph into a car doing 70 mph, and the 'closing speed' is 60 + 70 = 130 mph. If they pass each other (ignoring for now the changes due to a small sideways space between them - imagine they could pass each other on the same line, like they have zero width), that remains 130 mph relative velocity. No signs even change.

What is more, you can do the math w.r.t. one of them. Say the 60 mph one. Then it is 'going at' 0. The ground is going at 60, let's call that in the positive direction. The other car is going +130 mph. They pass. As they pass, the numbers don't change. After they pass the numbers are the same. The velocity of the ground is still +60. The other car's velocity is still +130 mph. It is now going away, rather than approaching, but it is still going in the same direction. One of your many mistakes is to think that 'coming towards me' is the opposite direction to 'going away from me'. They aren't opposite directions if they're happening on opposite sides of you.

If they were travelling along the highway in the same direction on different lanes, they would have a relative velocity of 70 - 60 = 10. That wouldn't change either. From our 60 mph car, another would be passing at 10 mph. It would approach at 10 mph. It would leave at 10 mph.

What changes a velocity is called 'acceleration'. One of the cars would start going from 70, to, you know, 70.0000000000000000001 mph, etc., due to an imbalance in the force of its engine over the losses due to aerodynamic drag and other mechanical friction.

Just read what you wrote again. Diametrically wrong physics ending up with just meaningless garbage. Stop writing garbage and bragging about how clever you are (at least choose one or the other)!!!
 
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