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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
Naej:
--- Quote from: electrodacus on July 17, 2022, 01:10:52 am ---
--- Quote from: Naej on July 17, 2022, 12:53:43 am ---Did you read Newton's second law?
I think you distract yourself when there are 2 speeds involved.
--- End quote ---
It seems you do not understand what it means for a vehicle to be connected to two mediums at different speeds and to be powered by that difference.
Such a vehicle can not exceed the delta between those two speed without using energy storage.
--- End quote ---
Now you quoted Newton's 420th law, but not the 2nd.
--- Quote from: electrodacus on July 17, 2022, 01:10:52 am ---
--- Quote from: Naej on July 17, 2022, 12:53:43 am ---The computation was simple, but ok.
How about this: one limo A at 10m/s its wheels are connected to a 1kW generator, another limo B is next to it at 11 m/s with a 1kW electric engine connected to the generator.
Which limo accelerates/decelerates?
--- End quote ---
Sorry but I do not understand your problem. Please be more specific.
Limo A is at this time at 10m/s. I guess there is no engine or anything it was just pushed at 10m/s and there is no friction.
What is with the 1kW generator ? is that connected at the wheel and just dumps 1kW as maybe heat in to a resistor ?
What is the weight of lima A ? without that there is not enough data to provide an answer to your question.
Limo B "1kW electric engine" do you mean 1kW electric motor maybe powered by a battery ? and then this is "connected to the generator" ?
--- End quote ---
The electric generator is connected on limo A wheels and produce 1kW (say 1kV, 1A DC). Regenerative breaking if you will.
The 1kW electric engine is connected on limo B wheels and powered by limo A's electric generator.
10t limos.
So, will the fast limo get faster, and the slow one slower? Or the reverse perhaps?
PlainName:
--- Quote from: Nominal Animal ---If you have many of them in parallel too, then the velocity of each individual marble is low, but the number of marbles pushed in and out huge. If you knock one marble in, it takes only a tiny fraction of a second for the outermost marble to ping correspondingly, even though the velocity of any individual marble is very low. (Consider, in particular, how the length of the marble chain doesn't really affect much how long that takes.)
--- End quote ---
I don't think that's correct. [But it may be - see next post]
The motion in a cat's cradle is propagated via a shockwave, which presumably would be the speed of sound in the material. It just looks instant because the line of marbles is so short.
In the situation you suppose where there are many parallel lines and consequent large capacity of marbles, the output is no faster than the input unless the output is restricted by a bottleneck. Then the many marbles must all pass through a smaller outlet in the same time and you get an increase in speed, but only at the outlet and the speed between individual marbles in the parallel rows would still be the speed of the shockwave down the line.
PlainName:
I think I may have misunderstood the proposition. I assumed that any marble in the cat's cradle would do as the initial one, for the purposes of tracking motion, but I think instead you mean the one you swing, which does obviously move slower than the shockwave in the chain.
So, yes, the first marble would be slow and the last seem to be moved almost simultaneously. But I am not sure that represents the electron situation. Specifically, I am missing the first swinging electron - perhaps there isn't one, or I and seeing it and not recognising it.
cbutlera:
--- Quote from: Nominal Animal on July 17, 2022, 12:34:41 am ---
--- Quote from: cbutlera on July 16, 2022, 11:57:34 pm ---
--- Quote from: Nominal Animal on July 16, 2022, 09:49:38 pm ---
--- Quote from: imo on July 16, 2022, 09:39:22 pm ---We have got something like Planck scale, time, force, length, energy, temperature, volume, area, density, frequency, momentum, acceleration.. Why we cannot define the smallest blobs of energy then?
--- End quote ---
I do believe Feynman was making the same point as Magritte, when he painted "This is not a pipe".
--- End quote ---
I don't see Feynman playing with words in that way.
--- End quote ---
It is not wordplay. It is a fundamental idea of what physics and mathematics are. Philosophy, not wordplay.
--- Quote from: cbutlera on July 16, 2022, 11:57:34 pm ---I may see one Joule apparently moving from A to B. Someone looking at the same event from a different reference frame may see five Joules apparently moving from B to A. So what is this thing that moved?
--- End quote ---
Right. Physics models the observations, and never tries to explain what 'that thing that moved' is; only quantify it and describe how it behaves.
--- End quote ---
"It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity, and when we add it all together it gives “28”—always the same number. It is an abstract thing in that it does not tell us the mechanism or the reasons for the various formulas." - Richard Feynman.
To me, it is clear what Feynman is saying here, and it is exactly the reason that I quoted him in the first place. He is warning us that knowing the name of something and knowing how it is represented and modelled in some mathematical space, is not understanding the reality of it. Trying to form a visual image of it as something that can flow from place to place will very likely lead one astray. As has been amply demonstrated in this thread.
I hadn't thought too much about the pipe before, so my earlier response was just to compare the obvious superficial message in the painting to Feynman's statement. But having researched the painting a little more I agree with you, there is a similar warning there. I have no eye for art, so any subtle message it contains usually goes straight over my head, unless it is pointed out to me.
electrodacus:
--- Quote from: Naej on July 17, 2022, 08:48:56 am ---The electric generator is connected on limo A wheels and produce 1kW (say 1kV, 1A DC). Regenerative breaking if you will.
The 1kW electric engine is connected on limo B wheels and powered by limo A's electric generator.
10t limos.
So, will the fast limo get faster, and the slow one slower? Or the reverse perhaps?
--- End quote ---
Thanks for clarifying.
Obviously the limo A will go slower as it converts his kinetic energy in to electrical energy that is then transferred through wires to limo B witch will use that electrical energy to increase kinetic energy by the amount limo A has lost.
You will need a very long cable as the distance between the two limos will increase over time.
But what is even the point of this example.
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