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Author Topic:   Quick Questions, Short Answers - No Debate
dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 51 of 341 (615697)
05-15-2011 7:45 PM
Reply to: Message 47 by Dr Adequate
05-15-2011 2:31 PM


Re: Propulsion in the vacuum of space; the true story
Negatory, good buddy! Conservation of linear momentum.
Linear momentum is mass times velocity. Expell part of that mass (AKA reaction mass, which is why they're called "reaction drives") at high velocity in one direction and that will result in a change of velocity in the other direction. Nothing pushes against anything else.
A common example from a related principle, conservation of angular momentum, might help. There, angular momentum is the product of angular velocity (how many degrees/radians/grads per second the body is rotating) and the moment of inertia, which is analogous to mass. Actually, the moment of inertia, I, is a good source of integral calculus problems, if you're thinking of writing a math textbook. It is the infinitessimal summation of the products of infinitessimal points of mass times their distance from the axis of rotation. The farther out mass is distributed, the greater is I, and the closer in it's held, the lesser is I.
Skaters and dancers use this principle all the time. In your office swivel chair, extend your arms and legs out (high I) and have somebody start you to slowly spin. Angular momentum is that initial rate times your high I. Now pull your limbs in tight, suddenly lowering I. To keep angular momentum constant, angular velocity increases and your spinning speeds up. At any point that you want to stop, simply increase I by extending your limbs out again. Works every time!
http://en.wikipedia.org/wiki/Rocket#Physics (though it also graphically plays on the idea of forces pushing on all walls of the combustion chamber except for the exhaust hole):
quote:
As a side effect, these pressures on the rocket also act on the exhaust in the opposite direction and accelerate this to very high speeds (according to Newton's Third Law).[1] From the principle of conservation of momentum the speed of the exhaust of a rocket determines how much momentum increase is created for a given amount of propellant. This is called the rocket's specific impulse.[1] Because a rocket, propellant and exhaust in flight, without any external perturbations, may be considered as a closed system, the total momentum is always constant. Therefore, the faster the net speed of the exhaust in one direction, the greater the speed of the rocket can achieve in the opposite direction. This is especially true since the rocket body's mass is typically far lower than the final total exhaust mass.
As the remaining propellant decreases, rocket vehicles become lighter and their acceleration tends to increase until the propellant is exhausted. This means that much of the speed change occurs towards the end of the burn when the vehicle is much lighter.
It is also covered in Chapter 8, "Conservation of Linear Momentum", of my physics textbook, Fundamentals of Phsics, by Halliday and Resnick, Revised Printing, 1974, John Wiley and Sons, $13.50 in 1977 (present-day students, eat your hearts out), as Example 7 starting on page 145.
PS
On the subject of conservation of angular momentum, I just have to share this one dance move. It was taught to me by a West Coast Swing teacher.
Fan moves are common. That's when you're turning supported on a bent leg with the other leg straight describing a circle on the floor. OK, you go into a fan, but then you draw that extended straight leg in, which greatly speeds up your turn, after which you extend that leg again to slow your spin down. And maybe get one more speed-up in if you're lucky (keep in mind the frictional losses through the contact between your supporting foot and the floor).
Looks phenomenal when you see it.
Edited by dwise1, : PS

This message is a reply to:
 Message 47 by Dr Adequate, posted 05-15-2011 2:31 PM Dr Adequate has replied

Replies to this message:
 Message 52 by Dr Adequate, posted 05-16-2011 12:33 AM dwise1 has replied

dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 53 of 341 (615721)
05-16-2011 1:16 AM
Reply to: Message 52 by Dr Adequate
05-16-2011 12:33 AM


Re: Propulsion in the vacuum of space; the true story
I do not see your explanation at all describing the action of the conservation of linear momentum.
Consider ion drives, which are also reaction drives. Electric grids accelerate ions to form the exhaust. Where is the pushing there? Acceleration of the vehicle is by conservation of linear momentum, not by pushing against the sides of the chamber.

This message is a reply to:
 Message 52 by Dr Adequate, posted 05-16-2011 12:33 AM Dr Adequate has replied

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dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 58 of 341 (615749)
05-16-2011 11:30 AM
Reply to: Message 57 by Percy
05-16-2011 10:24 AM


Re: Propulsion in the vacuum of space
To understand the role of the conservation of linear momentum in rocket propulsion, calculus is required.
Thrust is based on the rate of mass lost per second. The mass lost per second and the velocity at which it leaves the rocket gives that lost mass, which is the exhaust, a linear momentum directed rearwards which is balanced an acceleration forwards of the rocket body which is losing the mass of the exhaust.
More simply put, linear momentum L is equal to mass m times velocity v (a vector, so it has both direction and magnitude). So in
L = mv, for L to remain constant while m is decreasing, v must decrease. dv/dt = acceleration. And if that loss of mass is due to separation (eg, rocket exhaust), then the subtraction of that mass' linear momentum (subtraction since it's in the negative direction; remember, v has direction) has to be balanced by the addition of momentum to the rocket body in order to keep the overall momentum constant.
It's basic physics. http://en.wikipedia.org/...m#Conservation_of_linear_momentum
For a more complete, rigorous, and hopefully more enlightening explanation, I would recommend consulting physics books and introductory books on the physics of rocketry, but only those that employ calculus. Or to chat with a physicist about it. Otherwise, we will be violating the title of this topic.
PS
I had already stated my reason for adding angular momentum to the discussion. That was explicitly because it is much easier to change the "mass" term and to observe the effects of that change on the "velocity" term. To keep the product of two terms constant, if you reduce one term you must increase the other term, and vice versa. In playing with angular momentum, you can directly experience that that idea is far from abstract.
Edited by dwise1, : PS

This message is a reply to:
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dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 78 of 341 (615885)
05-17-2011 9:28 PM
Reply to: Message 75 by crashfrog
05-17-2011 10:39 AM


Re: Propulsion in the vacuum of space
Oh wow! The Bootstrap Drive!

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dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


(1)
Message 97 of 341 (632578)
09-08-2011 4:10 PM
Reply to: Message 92 by RAZD
09-08-2011 11:48 AM


Re: Flat Earth
In addition, I would think that the dip angle (not listed as such, but idea is included in the article on the horizon) might work.
One visual clue that we were taught about is how a ship leaving port appears to disappear as it goes over the horizon but its upper superstructure remains visible. This also comes into play when two ships at sea need to be within a particular distance of each other to begin to see each other; the top of the mast is always the first part to appear. The higher up the observer is, the farther out he can spot something, which is why a lookout would be placed in the crow's nest and why search radar's antennas are placed high on the ship.
In astronomy, the horizon extends out horizontally from the observer; ie, at right angles to the vertical. The true horizon, where the sky meets the ground, is below that. At what angle lower (AKA "dip angle") depends on the altitude of the observer (the greater the altitude, the lower the dip angle) and, if I recall correctly, on the radius of the earth (the smaller the radius, the greater the dip angle).
The mathematics can be left as an exercise for the student.

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dwise1
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Posts: 5930
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Member Rating: 5.8


(1)
Message 232 of 341 (655732)
03-13-2012 3:08 AM
Reply to: Message 228 by foreveryoung
03-13-2012 1:12 AM


Re: Looking for info on scientists in ID camp
A little perspective, perhaps.
I work as a software engineer, doing the software for embedded systems (hardware systems that are driven by a microprocessor, far more common than most people know). Before working on my computer science degree, I was a foreign language major, primarily German.
One of my German professors, a PhD, once shared with us his blue-collar father's views, that he, as a blue-collar "Joe", knew a little about every thing, whereas his son, the PhD, knows everything about nothing. In other words, PhDs are very highly educated, but normally within narrow fields. When a PhD says something pertaining to his own field, he should know what he's talking about. But when he says something completely outside his own field, his doctorate doesn't really lend any support there. For example, disregarding the "diploma mill" issues, "Dr." Kent Hovind has made many "scientific" claims and statements and his followers figure that since he's a PhD then he is a scientist. Well, his PhD, whether valid or not, was in Religious Education. Has nothing to do with science. In comparison, back in the 1970's there was a commercial depicting a cocktail party where a medical situation arises and somebody calls for a doctor and a doctor steps forward, a PhD in Musicology (as per Peter Schickele, made infamous by P.D.Q. Bach: "Those who can, do. Those who cannot, teach. Those who cannot teach become musicologists.").
So, back to your question:
So the only scientists that count who believe in ID are those in the biological sciences who have done post doctoral work?
It is a question for the biological sciences. So are you going to accept as pertinent or as questionable the objections of someone with a PhD in religious education? That is not a rhetorical question.
Here's an infamous example. Fred Hoyle was a well-known astronomer. He made some well-known probability arguments, including the "tornado in a junkyard randomly assembling a 707". They were complete bullshit; he didn't know what he was talking about. Hoyle knew something about astronomy, but he didn't know anything about biology. Does his expertise and reputation in one field transfer over to an entirely different field? Uh, no, unless he can demonstrate knowledge of that other field, which Hoyle did not do.
Of course, we do have Jonathan Wells, PhD in Molecular and Cell Biology from Berkeley. A member of the Unification Church, his expressed purpose for getting his PhD was in order to oppose evolution and in very short order he joined the Discovery Institute, etc. A parallel story is that of Steve Austin of the Institute for Creation Research (ICR). The ICR financed his education, during which he would publish under the pseudonym of "Stuart Nevins." He used that pseudonym to cover up his identity to his professors. During that time as a post-graduate student, he made many statements and claims that any lower-division under-graduate would have immediately known was completely and utterly false. Now as an in-house PhD for the ICR, his main claim to fame is in setting up situations that any geologist would know would create false dates, which means that he is deliberately creating "anomalous dates".
Both Wells and Austin have agendae outside of science. And they have both demonstrated a willingness to prostitute the truth in favor of their agendae.
OK, those PhDs in favor of ID. That has to do with the biological sciences. How many of those PhD's are in the biological sciences? What is said by those PhDs in the biological sciences? What does it matter what is said by the PhDs in the law, or even by Phillip E. Johnson, the father of Intelligent Design? Whose main objection against evolution is that "it leaves God with nothing to do." (I did honestly and truly read that article by Johnson, but have not been able to find it since then).
OK, then, just exactly why do you question biological sciences expertise in a question that intimately involves the biological sciences?

This message is a reply to:
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dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 254 of 341 (656742)
03-21-2012 3:46 PM
Reply to: Message 252 by RAZD
03-21-2012 9:35 AM


Re: regarding CrytoGod thread Is evolution based on empirical science?
Somebody needs to point him to the recent discussion of cladistics so that he can understand why his "but they're still fruitflies!" complaint is so incredibly lame.
And what's with his name? Goggle'ing, all I could find on "Cryto" is:
quote:
Demon of Vanity, is a powerful demon who grants youth,
beauty, and health in.
I always knew that fundamentalists were really and very seriously into demonology, but isn't this carrying that obsession a bit too far?

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dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 294 of 341 (661118)
05-02-2012 10:37 AM
Reply to: Message 293 by Percy
05-02-2012 10:25 AM


Re: The Pound Sign
I seem to recall it being used in carpentry to designate nail size, though the term used was "penny", I might guess referring to the nail's pennyweight. For example, 8-penny nails were often used, but 16-penny nails are what you would use when framing a wall.

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dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


(2)
Message 316 of 341 (667721)
07-11-2012 3:44 PM
Reply to: Message 314 by Coragyps
07-11-2012 3:14 PM


Re: Thee
Ye
In Early Modern English, the second person singular pronouns in the nominative, dative/accusative (there called "oblique"), and genitive cases were:
thou, thee, thy/thine
The second person plural pronouns for the same cases were:
ye, you, your
The same article also lists tables for the personal pronouns in Middle English and in Old English, so you can see the development of the forms over time.
So we see in the development of Modern English, the second person singular form was replaced by the second person plural. Why was that? The article suggests that the same thing that happened to French also happened to English, which was influenced by French:
quote:
The practice of matching singular and plural forms with informal and formal connotations is called the T-V distinction, and in English is largely due to the influence of French. This began with the practice of addressing kings and other aristocrats in the plural. Eventually, this was generalised, as in French, to address any social superior or stranger with a plural pronoun, which was believed to be more polite. In French, tu was eventually considered either intimate or condescending (and, to a stranger, potentially insulting), while the plural form vous was reserved and formal. In Early Modern English, ye functioned as both an informal plural and formal singular second-person nominative pronoun.
So then, in English we've lost the informal form. The creation of forms such as Y'all (contraction of "you all") to create a second person plural is one response to the situation, though it addresses our inability to distinguish between "you" in the singular vs the plural, rather than the lost distinction between familiar and polite forms, which we apparently don't care that much about anymore anyway.
BTW, if you want to follow the links to the terms in that quote, go to the page whose link appears at the top of this message.
FWIW, yes, I'm a language geek.

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dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


(2)
Message 329 of 341 (667835)
07-12-2012 3:52 PM
Reply to: Message 322 by Chuck77
07-12-2012 7:07 AM


Re: Creation Model
Actually, the "Scientific Creation Model" already exists and has existed since 1978.
In the first issue of Creation Evolution Journal (Vol 1, Num 1, Summer 1980), Frank Awbrey's article, Yes, Virginia, There is a Creation Model, stated:
quote:
Though creationists carefully avoid stating their model in debates, thereby keeping themselves off the defensive, they have one nonetheless. Here it is in bold outline as extracted from their books and publications.
The rest is the Scientific Creation Model, which, despite creationists' adamant denial of it being religious or based on religion, is blatantly and obviously just a slightly sanitized rehash of their literal belief in Genesis.
The bibliography of that article (not included on-line) led me to an article by ICR lawyer Wendell Bird that was published in Acts & Facts in December 1978. I researched that at a library, verified that Awbrey accurately stated what it stated, and also gleaned from it the "Biblical Creation Model". What Bird was doing was contrasted their "Biblical Creation Model" with their "Scientific Creation Model" in order to show that the "Scientific Creation Model" was not the least bit religious. What he instead demonstrated was that the two were identical except for superficial changes in wording, which I'm sure would be deemed sufficient by a lawyer to change reality. You can see that for yourself on my web page at http://cre-ev.dwise1.net/cmodel.html.
Bird's article is cited very widely, including in the US Supreme Court's decision in Edwards v. Aguillard (1986) which found "creation science" to be thinly disguised religion and hence cannot be taught in the public schools. The immediate result of that ruling was for creationists to shift from their game of "Hide the Bible" (which Bird was playing in his article and upon which the entirety of "creation science" is based) to a new game of "Hide the Creationism" as they started using "intelligent design" as their new smokescreen (the infamous editing of the creationist book, Of Pandas and People, into an ID book being a prime example).
One big problem with your proposed endeavor is that "creation science" has already thoroughly poisoned the well. We've already witnessed what large numbers of the best and brightest of creationists have been able to accomplish towards your goal, which is nothing whatsover except for lies and deception. Their resounding failure to produce any actual evidence dooms your own attempt to the same fate, hence the poison.
Still, it is good that you want to make that effort. I would recommend that first you lay down your goals, far more specific goals than you have just presented. Just exactly what is it that you want to accomplish? Do you want to come up with actual scientific evidence that supports your presumably literalist interpretation of Genesis? Do you want to come up with actual alternative explanations for physical phenomena so as to bring them in line with your presumably literalist interpretation of Genesis? Just exactly what are your goals here?
Assuming your answers to my question are "yes", then you need to lay down in sufficient detail the specific interpretation of Genesis that you seek to support. And you will need to translate that into scientific terms, mainly what physical events had to have occurred and when. That will be needed in order to determine what kind of scientific evidence you would expect that would support your particular interpretation of Genesis and, more importantly, what scientific evidence would show your particular interpretation of Genesis to be wrong -- otherwise, how could you possibly ever test your "model"?
And far more important than that, what will you do when the evidence stacks up against your particular interpretation of Genesis? The standard reaction of creationists has been to seek to change the evidence, which led directly to their descent into deception and pathological lying. Will that be your own response? Or will you allow for going back and correcting your interpretation of Genesis to better conform with the truth? With reality. Of course, that could also require you to go back and rethink some of your theology, which I assume places impossible demands on the truth of a particular literalistic interpretation of Genesis and its relationship to what you believe about the rest of the Bible and to the entire structure and validity of your faith.
A thought for you to consider: just how scientific was the Bible ever supposed to be? It would reflect the views and ideas about the universe and its origins and how it works that were held and understood by the people at the time it was written. Remember what was said about "spiritual meat" and "spiritual milk" and how you would not feed an infant meat, which he's not yet able to digest, but instead milk which he can. Similarly, what would you feed a pre-scientific people, scientific meat or scientific milk?
Expecting the Bible to contain fast and hard scientific information just does not make any sense. And expecting to develop a "scientific creation model" in support of your particular interpretation of Genesis would be like expecting to develop a scientific model of human reproduction based on stories of storks and cabbage patches.
To recap, your intentions appear to be both honorable and laudable, but your quest is folly.

This message is a reply to:
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