michel123456

I don't think it is ignorance. "Never underestimate the ennemy". Don't misunderstand me, Dave is not an ennemy. But when a scientist believes he is fighting ignorance most of the time he is not. The real ennemy is incomprehension. Incomprehension is not a matter of intelligence or ignorance. Incomprehension means the discourse of the one is not received by the other. Incomprehension turns on both sides: and from the "ignorant", and from the "scientist". When the "ignorant" ends the conversation in total refutal, the scientist is sad. When the scientist ends the conversation in refutal, the "ignorant" is pissed. They both lose.

I hope I got it. Labelling of both diagrams is unclear. In fig1, I understand vertical & horizontal axis are distances. In fig2. the upper part looks to have horizontal axis representing velocity, the down part as far as I understand velocity is the vertical axis. Or I miss something.

A boiled egg floats, but a fresh egg sinks. So you can go at sea and sink a fresh egg to make your experiment. Unless you want pressure by air and not by water. It is supposed impossible to break an egg by pressing in the palm of a hand. Be careful doing the experiment.

Hey, where are you going?

Dave is a skeptic, that is good. He is interested, that is good. He disagrees, that is good. There is nothing more annoying than 2 people agreeing: nothing new will come from such a situation.

I have to admit I waited a while before posting. It's not good killing a thread at post #2.

My advice: use graphs, images, pictures to improve communicabilty.

I remember objects like a table lamp made from human skin, at the Buchenwald camp I visited in 1976 if I remember correctly. That was not a joke. ----------- see Ilse Koch.

Don't take that too seriously. Yes it is childish, but it has effect. Think that my post was only one number: what power! And I think my previous posts were polite. The deep question is that it has been showned that previous animation was wrong. It is a very bad habit to show to a child what he cannot do. You always must show the right way, not the bad one. I am patient.

Why "extra weight of water"? Continents must have an average density higher than water, I suppose. IOW water is not "heavy" compared to anything else. If water was so heavy, the crust would be thicker under the oceans, which is not the case. I mean heavy are the continents, not the oceans. The rebound is connected to the loss of weight of ice upon continental masses, not about an increasing or decreasing depth of the seas.IMHO.

9

You can't be serious.

Good luck.

I have wood in my head. Staying in my own FOR, without frame switch, observing an object that moves at close to c speed, don't I observe length contraction & time dilation of this object?

The video is showing a leak in a small town road, producing a 10 m high jet. I am not an expert. I suppose on long distance and for large debit open air canals are more efficient. But you have to begin from an elevated source, like a barrage in a mountain somewhere. I would say first make the quantitative estimate of the demand, so you can get an idea of the dimensions you need. Maybe I drive you in the wrong direction, I have no idea how big this developement is.

From source to treatment plant there may be several kilometers. the water in those ducts (or canals) is 'dirty'. This same water will go into the lake; it is not drinkable water. But it must be protected from contamination like pesticide & other chemical products. It means the whole area that concerns the lake must be under supervision, no industries, no settlement, maybe no agriculture, in other words, nothing at all in a restricted closed area. _Canals are used when possible, it is not easy to design, you may need bridges (aqueducts) and other technical works. Water In Athens -Greece (4millions inhabitants) comes from 192 km away through such a canal crossing mountains. Underground pipes are possible, but you will never allow to build anything upon it, except road. Pressure meters at intervals will indicate the leak quite easily. Also, because water is under pressure (closed pipes), the leak may appear as a regular fountain. http://www.youtube.com/watch?feature=player_embedded&v=Qz-AqE725ao

Log out. Log in. Usually it helps.

edited & (deleted)

The correct relativistic animation would be instructive.

If this exercise is meant to ressemble real life, you need a political map first. All installations must be inside the district perimeter (see edit). -you need a plot (a piece of land) at the source. You need land for the ducts till the village: that can be under some roads, or next to roads, it is difficult and costly to expropriate land for ducts on kilometers (that depends on your political regime of course). You need a large plot near the consummation point for the water treatment plant. If you don't care of these elements, the cost will be outrageous. _theoretically, you should use gravity. The source should be at an elevated point. Then you can use open air ducts (canals) to transport raw water until the treatment plant that will be the closest possible to the village. The path must then be drawn on a topographical map with contour lines. In between, you should care for storage in open air tanks, or lake,(on communal plot) to buffer the demand. This can be an existing lake, if you have one. After cleaning water, use mechanical devices (pumps) to raise water in elevated tanks (water towers), in order to deliver clean water under pressure. Each water tank must be on a communal plot, that can be on squares or traffic circles for example. That's the easy part. If source is not elevated (the river), you must use pumps right from the beginning, ducts under pressure, and several points for re-pressure (I don't know the technical terminology), which mean cost in installation & maintenance. _I suppose modern design should include water recycling, since a huge amount of clean water is usually wasted. So your design should not stop at consummation. I am not an expert, I strongly suggest to get any possible information from other older students. If not available, bring flowers or sweets to your professor. Tell her from Michel. --------------- Basically, you need an urban survey. If there is no (you can't establish one by yourself), it will remain very theoretical, and maybe easier. --------------- edit. If the developpment is part of a large governmental (national) project, the municipality border is not an issue.

I don't understand fig.2. In this example, by definition speed is constant. Speed does not equal zero at M. Distance does. IMHO. Or I don't read correctly.

It was not intended to be "ad hominem". Statements like "use the Galilean velocity addition at low speed" and "use the relativistic composition of velocities at high speed" are a source of misunderstanding for everyone. Iggy, supported by Janus, Sisyphus, Spyman & Swansont (in alphabetical order, I hope I didn't miss anyone) have showned an example (closing speed) where Galilean velocity addition can theoretically reach 2c. I think it is a valuable information. And there is a difference between ignorance and non-understanding At this moment I know there is something I don't understand, although I understand the explanation. ......... Is that understandable?

FYI there is no freedom of speech on this Forum. I started a thread on the subject once. Welcome.

It would not be the first time a Professor ask his students to resolve a case he his engaged to solve for a third party in real life. Does your Professor maintain a consulting office out of academics?

There is no doubt I have a misunderstanding. But statements like "The Galilean world where you would simply use v + u is only an approximation, valid at low speeds" are there to increase the misunderstanding. In another thread, all of you experts show that in certain case, one MUST use the Galilean addition. That was about the case of closing speed, where you made me admit , IIRC, that relativistic addition is WRONG.