Re:Feasibiliy of High Speed Travel
on
X-43A Hits Mach 7
·
· Score: 1
no, that is not what that says.
what it says is that there is a _fundamental_ limit to the maximum acceleration that can be achieved, has nothing to do with spinning the tires, etc. this is assuming that you do not spin the tires at all, there is still an upper limit that is defined by your mass.
Re:Feasibiliy of High Speed Travel
on
X-43A Hits Mach 7
·
· Score: 1
i think that you misunderstood his (reasonable) question. the question is: is there enough "road" here on earth to actually fly this thing and take advantage of its mach 10 capabilities (while also taking into account for the limitations of a human being withstanding extreme forces). most ppl do not realize the tremendous physiological issue that fighter pilots deal with everyday.
as for your Cars of Tomorrow magazine, in fact what has changed is that the coefficient of friction for racing slicks is now 3 - 4. It was previously believed (and even still believed by many physics professors) that the c.o.f. was always less than 1. why does this matter? because physics _does_ say that a car that is propelled by frictional forces (i.e. tires) will never be able to accelerate faster than it's mass times it's c.o.f. doesn't matter how big the engine, how powerful the fuel, etc.
theoretical models HAVE been proposed, but they all make use of a) matter that is more dense than anything man has ever seen and b) a tremendous amount of energy, on the order of our Sun's total output.
Toluene and Xylene are both cheaper than 110 leaded octane race fuel. And in that case of the F1 turbo cars, they were running a mixture with heptane as a filler (in order to conform to the F1 rules at that time) which costs almost nothing.
Those cars were so darn fast (and unbeatable) that they revised the F1 rules by lowering the maximum octane of the fuel allowed; the turbo guys responded by simply lowering the boost pressure slightly and retarding the ignition timing by a degree or two. The result: still a whopping 900 hp.
So then F1 banned the turbos altogether, and we have the V10/V12 crowd that dominated F1 today.
As for "pump gas"...how much gas do you think a 5.7 L big block will go thru during a night of drag racing? How much do you think a turbo 2.0 L will use, and who will use it more effeciently? The import still wins on that side of things.
while your logic is correct in the sense of a "rule of thumb" you should also remember that some of the faster cars out there are now small displacement engines.
consider the 1987 Honda-McLaren car. it had a puny 1.5 L v6, destroked, with a massive turbo, yet it put out well over 1000 hp and something like 700 ft-lb of torque. In terms of hp per liter, no other car has ever come close. With the turbo doing all of the work, this was essentially a jet engine.
The reasons for this have to do with physics and airflow. If you think of a motor as nothing more than an airpump then the more air that flows through it will give you more power. This means that a larger engine isn't NECESSARILY better.
It also does involve COST, as you have pointed out, but incorrectly. If you include the cost of the car (in addition to the performance parts) you will find that hp per dollar, the big block route is in fact more expensive.
Not trying to start a war here, just offering my objective view, as someone who has been on both sides (big block & import).
Re:Van Allen belts?
on
Melting Europa
·
· Score: 2, Informative
actually the effect of the Van Allen belt was one of the greatest concerns for the Apollo mission planners.
They were able to get around it by a) going through a part of the Van Allen belt that has less radiation - some parts WOULD turn you into fried chicken (protons with energy on the order of 50 - 150 MeV - bad) and b) they passed through it quickly (i believe it was 4 hours), and scheduled the launch specifically around that window.
even so, they received rads far beyond what most of us will ever encounter (yet not enough deemed "immediately life threatening"). probably something like what someone would get living on a nuke sub for the duration of their service.
in short, the specific amount of radiation they received is categorized as being not immediately threateneing, but likely to cause cancer later.
have you been living under a rock? its not like china is going to come right out and say it, but analysts have been saying for the last few years that they have ICBMs pointed at us (around 12-15) with nukes.
how do you think they've been able to go into space for all these years?
and they didn't steal our secrets...clinton sold them!
your particular circumstances are one thing, but what about:
-the person who had the wrong leg amputated? -the infant in neo-netal who got the wrong blood type transfused? -the person who was given a "harmless" mercury-containing vaccine and promptly dies? -the person who goes in to get their tonsels removed and dies of an overdose of anaesthia because the anaesthiziologist was doing a line of coke in the bathroom (yes, it happened)?
who is to blame for situations like these that happen everyday, all around the country?
you know, if a truck driver does something stupid and kills somebody, he would probably go to jail. if it's a doctor, yes they will take a monetary hit in the wallet, but it's not going to make them have to sell their porsche just yet.
i love how everyone talks about this like they've actually been there, with the fancy answers and all.
the fact is that nobody knows where the water went.
for all we know, our own water may have come from mars. the theory that the moon was formed by a collision between the earth and mars is still up for grabs.
i do not disagree with anything that you are saying per se.
it is not completely "something for nothing". there will be energy expended and there will be energy lost.
will it require some extra energy to restore positive bouyancy? yes.
if i am at an altitude, and dive to gain speed, then pull up to climb again...i will not reach that exact same altitude (since i will have lost energy due to friction). but it would be "close". i could then just burn enough fuel to "make up the difference", rather than burning a whole tank of fuel in a traditional climb. what is wrong with that?
i cannot help but imagine (without having actually calculated any of this) that the energy needed to do this repeatedly is not nearly as high as, say, burning a bunch of kerosene for a short trip.
lets imagine that the plane is descending, and spinning its turbines. now a tail wind starts blowing...that tail wind energy could be contributed. now what if that tail wind happened to give just enough energy that we are right back where we started? we would have a complete cycle.
if nothing else, i see this scheme as a way of using what would otherwise be a great deal of wasted energy (much like in electric hybrid cars where braking adds charge to the battery), not "creating" energy, just making use of what would otherwise be wasted in going up and down.
if flight paths were limited to going with the major weather patterns, then do you disagree that this might be feasible?
i am not claiming it is, only that it seems possible.
i do not believe that the claim is being made that this is a perpetual motion machine - only that it would require vastly less energy than current technology based upon fossil fuels.
remember conservative fields? there is no net loss/gain of energy. in this case gravity is the conservative field.
now TRUE, there should be some small loss of energy due to friction, BUT the idea is to use some of that to restore the buyancy. if there is an additional wind present relative to it's trajectory then it might make up for this frictional loss of energy, and infact then the net consumption of energy would be zero (altho there would be other things like onboard electronics, and so forth that would consume energy also).
>float up out of the atmosphere and vanish into >space, with everything and everybody aboard!
interesting observation, but is that really true? if lift is being supplied by buyonancy then the atmospheric pressure is supplying the outside "positive" pressure. once you leave the atmosphere there isn't anymore such pressure so you would come back down.
also, since its essentially the act of preserving a vaccuum that is keeping it aloft, one would only need to bleed in air from the outside to come back down (i.e. "popping" the balloon). afterall, nature abhors a vacuum, right?
as you and just about everyone else has said, "show no bitterness"
this proves to your interviewer without a doubt that you, esteemed would-be-hire, are more than willing to take a good ass-pounding with a smile. god forbid that a little humanity might drip out onto the desk.
ever seen "office space"? thats what most of ppl's worthless lives consist of, worrying about "showing bitterness" or having to explain "gaps" on the resume.
im all of the ppl at enron who got screwed out of their pensions were told to keep their chin up and "show no bitterness". afterall, displeasure is for losers, right?
the UN has been trying to control the internet for some time now. The US doesnt want that. What's the problem? If you want open source, then just use it: we dont have to all bend over for the UN.
it is not that simple. most ppl are under the impression that the money that they pay in taxes is actually spent.
income taxes are used to pay the interest on loans that the U.S. treasury takes out from the federal reserve bank. our money goes nowhere except into the pockets of foreign investors who hold the purse strings of the USA economy. it is the growth of this defecit that is the cause of taxation in the first place: before 1913 there was no fed reserve and no income tax! unfortunately it is debt that was never meant to be repaid, since you cannot pay off debt with more debt...does Argentina come to mind?
cutting taxes has nothing to do with cutting hubble. neither democrats nor republicans are really honest about this issue, since they both spend a great deal of money, but at least i know that republicans are not going to wind up spending it on needles and worthless social programs.
the problem is a small detail involving the laws of thermodynamics (entrophy): it will always be easier to destroy than to create.
how much does it cost a terrorist to blow something up? how much does it cost us to prevent it?
likewise it only requires limited understanding to create something destructive, but to undo destructiveness will always be much harder. it is relatively easy for enterprising terrorists to make bioweapons with the current technology available; yet we still cannot cure even the simplest of diseases that afflict us, with the current technology available.
how many times must we hear this....
a quick primer on physics of solar system travel: the hardest object to reach in our solar system is THE SUN.
since the earth is rotating around the Sun at about 30 km/s you would have to fire rockets in the opposite direction to kill that velocity in order to reach the Sun: otherwise you wind up in a stable (albeit closer) orbit around the Sun. There's one catch: our rocket technology today can barely achieve the 12 km/s velocity needed to escape Earth's atmospher.
So when you come up with a solution, gimme a call and then we can all start "firing our garbage into the Sun" - right, lets spend a billion dollars to eliminate $5 of garbage, sounds like environmentalist reasoning to me.
the most likely method of implementation would be as a kernel module directly (too much trouble, and wouldnt work for non-OSS system) or by using bpf called from the daemon to sniff for SYN packets to the necessary ports. once the "sequence" was received, it could then open the "real" port.
a nice variation of this would be to use some time-based hash (such as something like secureid) to generate a different port sequence each time. this would diffuse the sniffing problem that oh-so-many slashdotters have already pointed out.
Slashdot Mirror
no, that is not what that says.
what it says is that there is a _fundamental_ limit to the maximum acceleration that can be achieved, has nothing to do with spinning the tires, etc. this is assuming that you do not spin the tires at all, there is still an upper limit that is defined by your mass.
i think that you misunderstood his (reasonable) question. the question is: is there enough "road" here on earth to actually fly this thing and take advantage of its mach 10 capabilities (while also taking into account for the limitations of a human being withstanding extreme forces). most ppl do not realize the tremendous physiological issue that fighter pilots deal with everyday.
as for your Cars of Tomorrow magazine, in fact what has changed is that the coefficient of friction for racing slicks is now 3 - 4. It was previously believed (and even still believed by many physics professors) that the c.o.f. was always less than 1. why does this matter? because physics _does_ say that a car that is propelled by frictional forces (i.e. tires) will never be able to accelerate faster than it's mass times it's c.o.f. doesn't matter how big the engine, how powerful the fuel, etc.
theoretical models HAVE been proposed, but they all make use of a) matter that is more dense than anything man has ever seen and b) a tremendous amount of energy, on the order of our Sun's total output.
Toluene and Xylene are both cheaper than 110 leaded octane race fuel. And in that case of the F1 turbo cars, they were running a mixture with heptane as a filler (in order to conform to the F1 rules at that time) which costs almost nothing.
Those cars were so darn fast (and unbeatable) that they revised the F1 rules by lowering the maximum octane of the fuel allowed; the turbo guys responded by simply lowering the boost pressure slightly and retarding the ignition timing by a degree or two. The result: still a whopping 900 hp.
So then F1 banned the turbos altogether, and we have the V10/V12 crowd that dominated F1 today.
As for "pump gas"...how much gas do you think a 5.7 L big block will go thru during a night of drag racing? How much do you think a turbo 2.0 L will use, and who will use it more effeciently? The import still wins on that side of things.
while your logic is correct in the sense of a "rule of thumb" you should also remember that some of the faster cars out there are now small displacement engines.
consider the 1987 Honda-McLaren car. it had a puny 1.5 L v6, destroked, with a massive turbo, yet it put out well over 1000 hp and something like 700 ft-lb of torque. In terms of hp per liter, no other car has ever come close. With the turbo doing all of the work, this was essentially a jet engine.
The reasons for this have to do with physics and airflow. If you think of a motor as nothing more than an airpump then the more air that flows through it will give you more power. This means that a larger engine isn't NECESSARILY better.
It also does involve COST, as you have pointed out, but incorrectly. If you include the cost of the car (in addition to the performance parts) you will find that hp per dollar, the big block route is in fact more expensive.
Not trying to start a war here, just offering my objective view, as someone who has been on both sides (big block & import).
actually the effect of the Van Allen belt was one of the greatest concerns for the Apollo mission planners.
They were able to get around it by a) going through a part of the Van Allen belt that has less radiation - some parts WOULD turn you into fried chicken (protons with energy on the order of 50 - 150 MeV - bad) and b) they passed through it quickly (i believe it was 4 hours), and scheduled the launch specifically around that window.
even so, they received rads far beyond what most of us will ever encounter (yet not enough deemed "immediately life threatening"). probably something like what someone would get living on a nuke sub for the duration of their service.
in short, the specific amount of radiation they received is categorized as being not immediately threateneing, but likely to cause cancer later.
have you been living under a rock? its not like china is going to come right out and say it, but analysts have been saying for the last few years that they have ICBMs pointed at us (around 12-15) with nukes.
how do you think they've been able to go into space for all these years?
and they didn't steal our secrets...clinton sold them!
your particular circumstances are one thing, but what about:
-the person who had the wrong leg amputated?
-the infant in neo-netal who got the wrong blood type transfused?
-the person who was given a "harmless" mercury-containing vaccine and promptly dies?
-the person who goes in to get their tonsels removed and dies of an overdose of anaesthia because the anaesthiziologist was doing a line of coke in the bathroom (yes, it happened)?
who is to blame for situations like these that happen everyday, all around the country?
you know, if a truck driver does something stupid and kills somebody, he would probably go to jail. if it's a doctor, yes they will take a monetary hit in the wallet, but it's not going to make them have to sell their porsche just yet.
see why some ppl are upset?
i love how everyone talks about this like they've actually been there, with the fancy answers and all.
the fact is that nobody knows where the water went.
for all we know, our own water may have come from mars. the theory that the moon was formed by a collision between the earth and mars is still up for grabs.
i do not disagree with anything that you are saying per se.
it is not completely "something for nothing". there will be energy expended and there will be energy lost.
will it require some extra energy to restore positive bouyancy? yes.
if i am at an altitude, and dive to gain speed, then pull up to climb again...i will not reach that exact same altitude (since i will have lost energy due to friction). but it would be "close". i could then just burn enough fuel to "make up the difference", rather than burning a whole tank of fuel in a traditional climb. what is wrong with that?
i cannot help but imagine (without having actually calculated any of this) that the energy needed to do this repeatedly is not nearly as high as, say, burning a bunch of kerosene for a short trip.
lets imagine that the plane is descending, and spinning its turbines. now a tail wind starts blowing...that tail wind energy could be contributed. now what if that tail wind happened to give just enough energy that we are right back where we started? we would have a complete cycle.
if nothing else, i see this scheme as a way of using what would otherwise be a great deal of wasted energy (much like in electric hybrid cars where braking adds charge to the battery), not "creating" energy, just making use of what would otherwise be wasted in going up and down.
if flight paths were limited to going with the major weather patterns, then do you disagree that this might be feasible?
i am not claiming it is, only that it seems possible.
i do not believe that the claim is being made that this is a perpetual motion machine - only that it would require vastly less energy than current technology based upon fossil fuels.
remember conservative fields? there is no net loss/gain of energy. in this case gravity is the conservative field.
now TRUE, there should be some small loss of energy due to friction, BUT the idea is to use some of that to restore the buyancy. if there is an additional wind present relative to it's trajectory then it might make up for this frictional loss of energy, and infact then the net consumption of energy would be zero (altho there would be other things like onboard electronics, and so forth that would consume energy also).
>float up out of the atmosphere and vanish into >space, with everything and everybody aboard!
interesting observation, but is that really true? if lift is being supplied by buyonancy then the atmospheric pressure is supplying the outside "positive" pressure. once you leave the atmosphere there isn't anymore such pressure so you would come back down.
also, since its essentially the act of preserving a vaccuum that is keeping it aloft, one would only need to bleed in air from the outside to come back down (i.e. "popping" the balloon). afterall, nature abhors a vacuum, right?
...deathtrap?
as you and just about everyone else has said, "show no bitterness"
this proves to your interviewer without a doubt that you, esteemed would-be-hire, are more than willing to take a good ass-pounding with a smile. god forbid that a little humanity might drip out onto the desk.
ever seen "office space"? thats what most of ppl's worthless lives consist of, worrying about "showing bitterness" or having to explain "gaps" on the resume.
im all of the ppl at enron who got screwed out of their pensions were told to keep their chin up and "show no bitterness". afterall, displeasure is for losers, right?
the UN has been trying to control the internet for some time now. The US doesnt want that. What's the problem? If you want open source, then just use it: we dont have to all bend over for the UN.
early chemical rockes used a silver screen to catalyze the combustion of h2o2
why some hypothetical 3rd planet? why couldnt it have just been mars colliding with the earth?
...we'll get to see all of the backdoors
uh yeah, until the tractors start running on ethanol or hydrogen that is...
as far as coping with the strains of space travel...just make the hot-female-to-male ratio 10:1 and include plenty of ecstasy...
i dunno u tell me. the entire public school system is the utopia of democrats.
it is not that simple. most ppl are under the impression that the money that they pay in taxes is actually spent.
income taxes are used to pay the interest on loans that the U.S. treasury takes out from the federal reserve bank. our money goes nowhere except into the pockets of foreign investors who hold the purse strings of the USA economy. it is the growth of this defecit that is the cause of taxation in the first place: before 1913 there was no fed reserve and no income tax! unfortunately it is debt that was never meant to be repaid, since you cannot pay off debt with more debt...does Argentina come to mind?
cutting taxes has nothing to do with cutting hubble. neither democrats nor republicans are really honest about this issue, since they both spend a great deal of money, but at least i know that republicans are not going to wind up spending it on needles and worthless social programs.
the problem is a small detail involving the laws of thermodynamics (entrophy): it will always be easier to destroy than to create.
how much does it cost a terrorist to blow something up? how much does it cost us to prevent it?
likewise it only requires limited understanding to create something destructive, but to undo destructiveness will always be much harder. it is relatively easy for enterprising terrorists to make bioweapons with the current technology available; yet we still cannot cure even the simplest of diseases that afflict us, with the current technology available.
how many times must we hear this.... a quick primer on physics of solar system travel: the hardest object to reach in our solar system is THE SUN. since the earth is rotating around the Sun at about 30 km/s you would have to fire rockets in the opposite direction to kill that velocity in order to reach the Sun: otherwise you wind up in a stable (albeit closer) orbit around the Sun. There's one catch: our rocket technology today can barely achieve the 12 km/s velocity needed to escape Earth's atmospher. So when you come up with a solution, gimme a call and then we can all start "firing our garbage into the Sun" - right, lets spend a billion dollars to eliminate $5 of garbage, sounds like environmentalist reasoning to me.
the most likely method of implementation would be as a kernel module directly (too much trouble, and wouldnt work for non-OSS system) or by using bpf called from the daemon to sniff for SYN packets to the necessary ports. once the "sequence" was received, it could then open the "real" port.
a nice variation of this would be to use some time-based hash (such as something like secureid) to generate a different port sequence each time. this would diffuse the sniffing problem that oh-so-many slashdotters have already pointed out.