|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Relativity question
Thanks! That clears it up....as far it can be cleared up....
Doink "Paul Winalski" wrote in message ... On Sat, 12 Nov 2005 12:00:33 -0800, "Doink" wrote: OK, Energy = Mass X Speed of Light Sq. I understand the principle, that this translates to a BIG number and thus a lot of energy is contained in matter. Yes, matter is essentially frozen energy. Stipulated. By I'm thrown by the SPEED of light thing. If something has a mass of 10 grams and I multiply it by 386,000 mph it doesn't make sense. Is there a scientific conversion from speed to some other unit????? How do you multiply mass times speed? Or is it just representational? Can the explanation be simplified? Doink. It all comes from the definition of energy. Let's start with speed. The speed of an object is the distance it travels in a unit amount of time. In standard MKS units, it's thus measured in meters/sec (m/s). Speed is equal to distance traveled divided by the time it took to cover the distance. Note we're dividing meters by seconds and there's nothing strange or odd about it. Acceleration is the change in speed of an object per unit time. It's thus measured in meters/second-squared (m/s**2). The force required to produce a particular acceleration is proportional to the mass of the object being accelerated. (F=ma). Hence the MKS unit for force, the Newton, is one kilogram*meter/second-squared (Kg*m/s**2). Energy is a force applied over a distance. Hence the MKS unit for energy, the Joule, is one Newton-meter, or one kilogram*meter-squared/second-squared (Kg*m**2/s**2). Power is energy expended per unit time. Hence the MKS unit for power, the Watt, is one Joule/second (Kg*m**2/s**3). Utilities sell electricity in energy units (power applied over time), which is why it's sold in kilowatt-hours (one kilowatt-hour is 3600000 Joules). So now go back to Einstein's formula: E=m*c**2. The MKS unit for E is the Joule, for m is the kilogram, and for c is meters/second. So you can see it all works out--we get Kg*m**2/s**2, the correct units for a Joule. -Paul W. ---------- Remove 'Z' to reply by email. |
#12
|
|||
|
|||
Relativity question
Sam Wormley wrote: oriel36 wrote: To Sam The so-called 'genius' of reducing the astronomical effect due to finite light speed to mathematical notation 'c' is just another way to conceal the geometrical roots of the insight byOle Roemer. For Gerald -- Measuring the Speed of Light http://www.colorado.edu/physics/2000...es/jupiter.jpg http://www.colorado.edu/physics/2000..._evidence.html The Romerian jewel of this particular refinement of Copernican heliocentricity is an observational effect.Using the rotation of the foreground Milky Way stars and observed supernova representing external parent galaxies,it is one of the most exciting avenues of astronomy since Copernican/Keplerian heliocentricity. You homocentric freaks won't even recognise how heliocentricity is inferred through retrogrades and being incompetent have diluted the Copernican insight to a worthless and self serving, cretinous,relativistic end. http://www.answers.com/topic/copernican-principle You are too dumb to recognise that dropping the stellar background from the motions of the planets and substituting the background with the annual orbital motion of the Earth infers heliocentricity.You freaks of humanity imagine that an observer on the Sun is required - "For to the earth they appear sometimes direct, sometimes stationary, nay, and sometimes retrograde. But from the sun they are always seen direct..." http://members.tripod.com/~gravitee/phaenomena.htm If you can live with that Newtonian garbage you can live with anything but don't even try to comprehend the Keplerian or Roemerian refinements to true heliocentricity. Go hug your telescopes but that is all you have but that never made a person an astronomer. |
#13
|
|||
|
|||
Relativity question
oriel36 wrote:
Sam Wormley wrote: oriel36 wrote: To Sam The so-called 'genius' of reducing the astronomical effect due to finite light speed to mathematical notation 'c' is just another way to conceal the geometrical roots of the insight byOle Roemer. For Gerald -- Measuring the Speed of Light http://www.colorado.edu/physics/2000...es/jupiter.jpg http://www.colorado.edu/physics/2000..._evidence.html The Romerian jewel of this particular refinement of Copernican heliocentricity is an observational effect.Using the rotation of the foreground Milky Way stars and observed supernova representing external parent galaxies,it is one of the most exciting avenues of astronomy since Copernican/Keplerian heliocentricity. You homocentric freaks won't even recognise how heliocentricity is inferred through retrogrades and being incompetent have diluted the Copernican insight to a worthless and self serving, cretinous,relativistic end. ILLUCID |
#14
|
|||
|
|||
Relativity question
"Doink" wrote in
: That's what I was looking for....A sort of scientific conversion unit. For my purposes, I don't need to carry out the formula, just be able to understand the relationship between what's expressed as speed figuring into a formula involving mass. Your explanation was exactly what I was looking for. Thank you! You can use any units you like as long as you are consistant. The most commonly used systems in science and engineering are either the cgs system as used by Hilton or the mks system. Mixing units gets you into trouble as NASA found out a while back when one of their Mars probes missed!! Klazmon. Doink "Hilton Evans" wrote in message ink.net... "Doink" wrote in message ... OK, Energy = Mass X Speed of Light Sq. I understand the principle, that this translates to a BIG number and thus a lot of energy is contained in matter. Yes, matter is essentially frozen energy. Stipulated. By I'm thrown by the SPEED of light thing. If something has a mass of 10 grams and I multiply it by 386,000 mph it doesn't make sense. First if your multiplying by just speed then you're using the formula incorrectly. Is there a scientific conversion from speed to some other unit????? How do you multiply mass times speed? Or is it just representational? Can the explanation be simplified? 1 erg (cgs unit of energy) = 1 gram x cm^2/sec^2. Notice this has the same units as kinetic energy i.e. mass x speed^2. 10 grams x c^2 = 10 x (2.997925x10^10 cm/sec)^2 = 9.0x10^21 ergs, or 9000 billion billion ergs. Don't try this conversion at home. -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com |
#15
|
|||
|
|||
Relativity question
Llanzlan Klazmon wrote:
"Doink" wrote in : That's what I was looking for....A sort of scientific conversion unit. For my purposes, I don't need to carry out the formula, just be able to understand the relationship between what's expressed as speed figuring into a formula involving mass. Your explanation was exactly what I was looking for. Thank you! You can use any units you like as long as you are consistant. The most commonly used systems in science and engineering are either the cgs system as used by Hilton or the mks system. Mixing units gets you into trouble as NASA found out a while back when one of their Mars probes missed!! Klazmon. The best unit of measurement that I have found is: Furlongs per fortnight. It features a long base measurement that can be expanded to a very long distance with out accumulating much error due to calibration and a long time base which can also reduce error due to the long base line. 8^)... Posted April First..... Doink "Hilton Evans" wrote in message hlink.net... "Doink" wrote in message news:VaidnRMEAvlO1OvenZ2dnUVZ_tKdnZ2d@trueband. net... OK, Energy = Mass X Speed of Light Sq. I understand the principle, that this translates to a BIG number and thus a lot of energy is contained in matter. Yes, matter is essentially frozen energy. Stipulated. By I'm thrown by the SPEED of light thing. If something has a mass of 10 grams and I multiply it by 386,000 mph it doesn't make sense. First if your multiplying by just speed then you're using the formula incorrectly. Is there a scientific conversion from speed to some other unit????? How do you multiply mass times speed? Or is it just representational? Can the explanation be simplified? 1 erg (cgs unit of energy) = 1 gram x cm^2/sec^2. Notice this has the same units as kinetic energy i.e. mass x speed^2. 10 grams x c^2 = 10 x (2.997925x10^10 cm/sec)^2 = 9.0x10^21 ergs, or 9000 billion billion ergs. Don't try this conversion at home. -- Hilton Evans --------------------------------------------------------------- Lon -71° 04' 35.3" Lat +42° 11' 06.7" --------------------------------------------------------------- Webcam Astroimaging http://home.earthlink.net/~hiltoneva...troimaging.htm --------------------------------------------------------------- ChemPen Chemical Structure Software http://www.chempensoftware.com |
#16
|
|||
|
|||
Relativity question
Llanzlan Klazmon wrote:
You can use any units you like as long as you are consistant. The most commonly used systems in science and engineering are either the cgs system as used by Hilton or the mks system. I've always been amused by the mixed units - there is no "unitary" system of units (which would be meters-grams-seconds: mgs) while there is a 1/100 meters-grams-second (cgs) and a meters-1000 grams-seconds (mks) system. Quelle bizarre. |
#17
|
|||
|
|||
Relativity question
Doink wrote:
By I'm thrown by the SPEED of light thing. If something has a mass of 10 grams and I multiply it by 386,000 mph it doesn't make sense. Is there a scientific conversion from speed to some other unit????? How do you multiply mass times speed? Or is it just representational? Can the explanation be simplified? The problem is that energy is a pretty abstract concept. You can't point to some place on a brick and say, "There's its energy," the way you can spread your hand against it and say, "That's its width," or pick it up and say, "That's how much it weighs." Nevertheless, if you drop a brick from shoulder height onto your foot, it'll hurt a lot and may break some bones if it's heavy enough, whereas the same brick if dropped from a height of an inch will merely make you look foolish. The only real difference between the two situations is the speed with which the brick hits your foot. In one case, the brick strikes your foot with a gentle thud, and in the other, it has had some time to build up speed and land on your foot with considerable impact. Some enterprising soul may have decided to try to quantify this effect, and rather than using his foot as the impact meter, decided to use some other absorbing substance. We might use styrofoam, for instance. If you drop a brick onto a block of styrofoam, it sinks partway in before coming to a stop. That's because the styrofoam exerts an upward force on the brick, and it take some time before enough force has been applied to bring the brick to a complete stop. If you stack two bricks, one on top of the other, before dropping them onto the styrofoam, the pile will sink further in (assuming you drop it from the same height as before), because the styrofoam exerts just as much force as before, and that same force has to be applied for more time to stop the greater brickage. For "ideal" styrofoam, we might determine that the indentation is just twice as deep as before; for a pile of three bricks (with therefore three times the brickage), it would be three times as deep; and so on. Alternatively, we could drop one brick as before, but from a greater height, and see how much higher we have to go before we also get twice as deep an indentation, or three times, or whatever. Again assuming that we have ideal styrofoam, we find that we need only drop it from twice as great a height, or three times, or whatever. As a result of these observations, we might define a new quantity, called *energy*, which is a measure of the impact with which the brick hits the styrofoam. Since it's proportional to brickage for a given height, and also proportional to height for a given brickage, we might assume that it would be proportional to brickage times height, and we would be right--except that we probably want a more dignified and general term for "amount of stuff" in the brick than "brickage." Following Newton, we use the term "mass." In that case, we can write E = kmh where E, m, and h stand for energy, mass, and height, respectively, and k is the constant of proportionality. What would that be? With hindsight, it is not so hard to see. If we were on the Moon, for instance, dropping a brick is not as painful as it is on the Earth, since the Moon's gravity is weaker. We might guess, then, that it is the Earth's gravity, denoted g, that is the constant of proportionality, which gives us E = gmh We emphasize that there is no obvious physical interpretation of this product of three quantities. It's not as though you're measuring the volume of the brick and therefore multiply the three dimensions. The energy is just a quantity we defined to measure a property of interest. Then again, we need not drop the brick. We can throw it from the side, and as long as we attain whatever speed was derived from gravity when we dropped it, we should get the same effect. To find out what that effect is, we need to find out what speed a brick achieves when dropped from a height of h. It turns out to be v = sqrt(2gh) where v is the square root function. In that case, we also have v^2 = 2gh, (v^2)/2 = gh, and then E = (mv^2)/2 which you might notice has the same units as mc^2 in Einstein's equation. In the mks system, mass is measured in kilograms, and velocity in meters per second. Thus, energy is measured in units of kilogram-meters-squared-per-second-squared, an ungainly mouthful that is given the special unit name of "joule." For instance, according to this formula, a brick with a mass of 1 kilogram and a velocity of 4 meters per second (about 9 mph) is 8 joules, since half of 4 squared is 8. You may have noticed that these formulas describe the energy of the brick at two different moments in time. The first gives the energy of the brick before it's been dropped, whereas the second gives the energy just before it hits the styrofoam (or your foot). We can put it another way: the first gives the energy due to the brick's position, which we call its potential energy; and the second gives the energy due to the brick's velocity, which we call its kinetic energy. It's better therefore to write them as we often do, as PE = mgh KE = (1/2) mv^2 where I've slightly reformatted the equations according to tradition. Incidentally, those equations can characterize the brick at different points throughout its fall, not just at the start and at the end. At the start, a brick's PE might be 16 joules, but since it's not moving, its KE must be zero. Conversely, as it strikes the styrofoam, its KE is 16 joules, but since its height is zero, its PE has to be zero, too. It's tempting to think that throughout the fall, the KE plus the PE must be 16 joules, and that thought turns out to be true: Although both KE and PE are constantly changing, with KE increasing and PE decreasing, they change in such a way that their *sum* is constant. Another way of saying this is that the brick's total energy is conserved. There's no reason why this *has* to be true--it's just our common experience that it *is* true. You can raise the brick back to its original height, thus restoring its PE--but then in order to do that, you have to use up at least 16 joules worth of energy. In fact, you have to exert more, the rest of it being wasted as heat. There are lots of conservation laws, by the way: conservation of energy, of linear momentum, of angular momentum, and so forth. Before Einstein formulated his theory of relativity, there was also a law of the conservation of mass. This seems pretty straightforward, since in everyday experience, you can't just destroy mass; we merely shuffle it from one place to another. We can burn wood, it is true, and in so doing, it seems to vanish, but careful chemical experiments demonstrated that what really happened was that the wood was oxidized and the loss of mass in the wood we burned was really transformation into carbon dioxide and other molecules that dispersed into the air. So it seemed that mass really was conserved. But then Einstein came along and demonstrated convincingly that mass was just another form of energy--albeit extremely concentrated. This was his famous formula E = mc^2. (Incidentally, that mass is relativistic mass. Physicists generally prefer to deal with proper mass, also known as rest mass, in which case the formula is the somewhat less pithy E^2 = p^2c^2 + m^2c^4, where p is the object's momentum.) Note, though, that this formula still gives energy in good old units of kilogram- meters-squared-per-second-squared, or joules. It is therefore entirely consistent with the definitions of PE and KE. By Einstein's law, we can make mass vanish, but in doing so, we produce an enormous amount of energy. In order to build up enough velocity to create 16 joules upon impact, we must drop a 1-kilogram brick from a height of about 1.6 meters (about 5 feet), assuming g = 10 meters per second per second. That same brick, if converted entirely into energy according to Einstein's formula, would yield an amazing 90 million billion joules. This conversion is what allows the Sun, for instance, to get such wholesale returns of energy from such a trifling investment of hydrogen (to paraphrase Twain for a moment). It works the other way around, too: We can create matter, provided we throw in enough energy. There's a catch, though. Whenever we create a particle, it seems we have to create its corresponding antiparticle. We can create an electron if we put in about a million electron volts of energy (electron volts are also units of energy, which are much smaller than joules and therefore convenient when dealing with subatomic particles), but we have to create the anti-electron, too, also known as the positron. There doesn't seem to be any way around this, and--you guessed it--this too has to do with conservation laws. Finally, an electron volt is called that because it's the amount of energy required to push an electron "the wrong way"--say, from a battery's positive terminal to its negative terminal--across a potential of one volt. In other words, to push an electron through a wire from the nubby end of a AA battery to its flat end requires an investment of 1.5 eV. You can see why electron volts are so tiny. Nevertheless, it's the same kind of energy, which is why you can create energy by using gravity (usually falling water instead of falling bricks), and using that energy to push electrons the wrong way--uphill, so to speak. Then you let them go the natural way, and they can power your appliances. -- Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#18
|
|||
|
|||
Relativity question
Brian Tung wrote:
Doink wrote: By I'm thrown by the SPEED of light thing. If something has a mass of 10 grams and I multiply it by 386,000 mph it doesn't make sense. Is there a scientific conversion from speed to some other unit????? How do you multiply mass times speed? Or is it just representational? Can the explanation be simplified? The problem is that energy is a pretty abstract concept. You can't point to some place on a brick and say, "There's its energy," the way you can spread your hand against it and say, "That's its width," or pick it up and say, "That's how much it weighs." Nevertheless, if you drop a brick from shoulder height onto your foot, it'll hurt a lot and may break some bones if it's heavy enough, whereas the same brick if dropped from a height of an inch will merely make you look foolish. The only real difference between the two situations is the speed with which the brick hits your foot. In one case, the brick strikes your foot with a gentle thud, and in the other, it has had some time to build up speed and land on your foot with considerable impact. This is what I found so scary about the OPs question. It isn't really about relativity at all but about basic classical kinetic energy. You can measure velocity more or less directly by Doppler shift, but without knowing the mass of the moving object there is no way to find its energy. Momentum delivered to the foot scales with velocity, but the energy delivered and damage inflicted scales with velocity squared. Some enterprising soul may have decided to try to quantify this effect, One place where the effects of kinetic energy are felt in ordinary life are the stopping distances for a car. The thinking time increases linearly with speed, but the distance needed to make an emergency stop by braking hard scales with the square of the initial speed. It would go some way to explaining the prevalence of high speed tailgating if many people have no idea how much further it will take them to stop at high speeds. Regards, Martin Brown |
#19
|
|||
|
|||
Relativity question
Martin Brown wrote:
This is what I found so scary about the OPs question. It isn't really about relativity at all but about basic classical kinetic energy. Tell me about it. I set out to write a reasonably short (well, four or five paragraphs, really) bit about why energy has the units it does, and I just couldn't close the explanation without all that extra text. (Really.) -- Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt |
#20
|
|||
|
|||
Relativity question
Sam Wormley wrote: oriel36 wrote: Sam Wormley wrote: oriel36 wrote: To Sam The so-called 'genius' of reducing the astronomical effect due to finite light speed to mathematical notation 'c' is just another way to conceal the geometrical roots of the insight byOle Roemer. For Gerald -- Measuring the Speed of Light http://www.colorado.edu/physics/2000...es/jupiter.jpg http://www.colorado.edu/physics/2000..._evidence.html The Romerian jewel of this particular refinement of Copernican heliocentricity is an observational effect.Using the rotation of the foreground Milky Way stars and observed supernova representing external parent galaxies,it is one of the most exciting avenues of astronomy since Copernican/Keplerian heliocentricity. You homocentric freaks won't even recognise how heliocentricity is inferred through retrogrades and being incompetent have diluted the Copernican insight to a worthless and self serving, cretinous,relativistic end. ILLUCID O.K. http://www.strangepersons.com/images/content/7404.jpg See that picture of Jupiter's moon Io,well there is an observational effect in that image directly related to Ole Romer's original discovery. The original discovery was known as the Equation of Light or Mora Luminis and refers to the positional adjustment due to the finite distance light travels. As the resolution is entirely geometrical and based on the variations in the heliocentric motions between Jupiter and Earth,the anomalous slowing down and speeding up of Io's motion as it orbited Jupiter was accounted for as an observation an effect,its motion neither actual nor an illusion.Looking at the image above of Io and its shadow,it true position as viewed from an orbitally moving Earth can only be considered from the point of view of a mean motion.Just like the Equation of Time equalises the variations in the natural unequal day to the equable 24 hour day then so does the Equation of Light equalise the anomalous motions hence the astronomical use of the word 'equation' which has nothing in common with its non geometric counterpart. So,let's take Newton apart - " Some inequalities of time may arise from the Excentricities of the Orbs of the Satellites; [etc.]... But this inequality has no respect to the position of the Earth, and in the three interior Satellites is insensible, as I find by computation from the Theory of their Gravity. " Opticks 1704 The inequality of times sure does from the motion and position of the Earth , Io happens to be Jupiter's innermost satellite and Roemer's insight has nothing to do with gravity. It is easier to comprehend Roemer's insight without having to go through the bluffing and blustering of Newton and I assume there are people who would not mind accepting the real challenge that Roemer's insight provides. The uncharted territory of modelling the positions of galaxies to the rotation of the foreground Milky Way stars using supernova data and Roemer's insight is breathtaking but the outlines of these mountainous regions for real human endeavor is still laid low by the manipulations of a 17th century theorist who had no feel for these things. All this rubbish of source dependence or homocentric observer depedence is really uneccessary for no such perceptions are astronomically demanded no more than the speed of sound and the passage of a jet plane requires that you jump from a plane view to an earth based view and grapple with what the person hears.It is not even that interesting and in matters of finite light speed,it is entirely useless. This era is more crucial than any else for a silence has descended borne of Newtonian/relativistic novelistic exhaustion,whether a number of people resolve to take a conceptual audit going right back to the transfer of pre-Copernican astronomy to Copernican heliocentricity,the golden opportunity to restore a much needed balance will be lost. It may be that Western empirical cancer will kill the astronomical discipline entirely and another civilisation will pick it up as happened before for no civilisation can live with this insincerity that hijacks genuine accomplishments and spins a myth from misconduct and intellectual fraud.That is what Newtonian ballistics applied to planetary motion amounts to. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Putting relativity to the test, NASA's Gravity Probe B experimentis one step away from revealing if Einstein was right (Forwarded) | Andrew Yee | Astronomy Misc | 0 | October 7th 05 05:09 AM |
GravityShieldingUpdates1.1 | Stan Byers | Research | 3 | March 23rd 05 02:28 PM |
A Question For Those Who Truly Understand The Theory of Relativity (Was: Einstein's GR as a Gauge Theory and Shipov's Torsion Field) | Larry Hammick | Astronomy Misc | 1 | February 26th 05 03:22 AM |
Foundations of General Relativity, Torsion & Zero Point Energy | Jack Sarfatti | Astronomy Misc | 2 | July 7th 04 04:32 AM |
Beginner question about gravity | Ed L. | Amateur Astronomy | 9 | November 12th 03 05:19 AM |