With my sentence "...orbit where the probe is not affected by the gravitational pull", I ment that there is a gravitational force acting on the probe, but a equal centrifugal force acting in the opposite direction so the sum of the forces is 0. (stable orbit)
In simplified theory the probe can then stay in orbit indefinetly without burning engines, etc, which is what I ment with "not affected by gravitational pull".
However in reality gas-friction, "gravitational waves", tidal energy, other bodies, etc, will remove/add kinetic energy and ultimately destroy the orbit.:(
My point is that it is not the *weight* that makes the probe do "better" in space than on earth; but rather friction from air or the ground caused by weight and/or size/shape of the probe.
When the probe is in space, the engine is not used to overcome the gravitational force afaik. A traditional rocket places the probe into an appropriate orbit where the probe is not affected by the gravitational pull (all forces equals zero), then the probe use its engine to increase its orbital velocity, and in doing that, increasing the radius of the orbit.
As I said, we have force equilibrium when the engine is not running - that is, the sum of all forces are 0. I am not talking about a vertical "launch", I am just talking about a sort of "horizontal" burn where the engine resides on a frictionless surface of some kind and there is no air. Then the engine should accelerete just as good as it does in space, even though it has "weight".
Say its mass is 1 kg and its weight is 1 million kg and the engine has a 1 N thrust. This means that the acceleration is, using a = f/m is:
1/1 = 1 m/s^2.
That weight of 1 million kg becomes a problem only if we have friction.
I mean that the surface is completely orizontal - that is, the "tunnel" lies in such a way that the probe/engine is not affected at all by gravity (there is no friction, and no air resistance, but the probe does not move until we turn on the engine). Then it would accelerate just as good as it does in space even though it has weight?
In atmospheric flights you also have problem with air friction.
>you're mixing up mass and weight.
The mass of the probe is the same in a zero-g environment, or on jupiter - it is the weight that is different, we both agree on that.
However, I still dont see why weight, in it self, is (always) relevant for the acceleration of the probe. When we calculate the resulting acceleration from the engines we only consider the mass of the probe and the engine thrust. Now imagine if we have the probe on earth in a vacuum tube floating on some zero-friction surface or magnetic field (we have force equlibrium). Then if the engine are turned on, they would accelerate the probe as much as they do in empty space even though the probe has weight, right? (now the gravitational force is counteracted by the force of the magneticfield, instead of the centrifugal force in orbit)
What I ment was that the weight has nothing to do with it per se (except that it can cause friction), however, if we remove friction (for example by some imaginary surface, magnetic field, or whatever) and air resistance (perfect vacuum tube) on earth, the ion engine would work just as well here on earth?
I believe you are wrong. The probe is not accelerating perpendicular to earths surface, it is accelerating in an orbit around earth. The force accelerating the probe can be anything, as long as it is more than the tiny deacceleration from friction in the thin gascloud that surrounds earth.
When a probe is in orbit around earth no force is required to eliminate the pull of gravity from earth, since this force is counteracted by the centrifugal force due to the circular motion around earth, and the probe stays in orbit (if we assume the friction from the gas in space is zero).
Using the formula you provided for gravitational force, and the formula for centrifugal force, you can calculate the necessary speed you must have to sustain a specific orbit, or virce versa. If you want to leave earth, you just simply have to increase your speed and this acceleration can be how big or small as you like.
I dont understand why they talk about the probe being (near) weightless in space in the same context as the engine beeing useful in space?
No matter where the probe is, it has got the same mass, and hence the same inertia. Low-thrust engines work good in space because of no friction and often no requirement on quick travel (if it is a non-manned spacecraft). On earth an ion engine would never work for several reasons, one beeing friction against air and ground, but none of them has to do with the weight of the vechile/probe?
The internet got substantially more data than that. Heck, only my ultra small hobby-company has around 1 TB on the internet. And privatly I have around 0.5 TB shared over the internet from home. Then add all other small hobby companies, billions of webpages, colocation-servers, communities, p2p-"seeders" etc etc, and it will quickly pass 230 TB data, many thousand times over.
I must say I agree with you. When I was a kid (which was not too long ago) I always got the prepackaged models and built the car or crane or whatever, and then sooner or later I would dismantle the model to use the parts for something more fun. Building a model from a schematic, following instructions correctly is educational, fun and can learn a great deal on how to build sturdy and stable lego constructions.
So as long as the kids gets several packages during the years (so they have lots of pieces:), I think there is no problem with model-packages.
I guess the dream-package for many older kids (and adults:) would be the various mindstorms robotics invention kits.:)
Well, I just think it is pretty obvious that they should have some kind of union, especially when something like this happends (that must have happend several times before).
I think the employees of EA/other programmers/game devs are stupid that they have not formed their own union and made union agreements with their employers. That would increase job security and give the employees a fair share of company profits, etc.
Yeah, I was a bit ironic/sarcastic. Where I live it is natural that all workers are connected to some kind of union (I believe more than 90% of the employees here are connected to some kind of union, and this includes management).
I cannot understand why it is not as common in the states? Why does unions have so bad reputation in the states?
LEGO! I always got LEGO for christmas, and I loved it - and I bet the kids today also love LEGO.
A tip: Buy the LEGO robot invention kit, and let the kids teach themselves both basics of engineering and programming while having lots of fun!:) (this can be a great gift for adults too..:)
The problem is not a big government. The problem is bad democracy. The government is supposed to represent the will of the majority - not the rich elite (or "base") ; as is the current situation in USA.
And thats where the kyoto agreement comes into picture.. It is therefor important that all/most of the countries can agree on pollution control measures to avoid companies moving in one direction or another.
1) You can probably not play online until the official retail date even with the retail version. So there is ABSOLUTELY no reason at all to by the game for 270 USD instead of downloading a copy from www.piratebay.org, and then purchase the retail version when it is officially available.
In Sweden, where piratebay is located, a BBS-related lawsuit years ago concluded that the BBS-administrator/owner could not be held responsible for "warez"/illegal-stuff traded on the BBS by the users of the BBS. The same is argued to be true for a torrent tracker. The tracker is simply viewed as the means by which you can share digital material to others. Now if the material is shared without the copyright holders permission, the responsibility lies with the uploaders and not the tracker administrators.
Furtheron, as everyone knows, no actual copyrighted data is transmitted through the tracker, so I guess it should be even more legitimate than a warez-BBS.:)
I sure do hope that everyone in my generation (born in the eighties and later) have realized that there simply are no "bad" words.
"Bad" words is a relic of religion and misplaced moral thinking, which has no place in the 21 century. I hope that we all will simply tell our children that there are no bad words and that they can say whatever they want. Afterall, the words they will be using is probably words you are using yourself anyways. I cannot understand why many parents think it is okay that they say "bad" words and at the same time think it is absolutely not okay when their kids does the same thing..
I download lots of tvshows, maybe 5-6/week, from http://www.tvtorrents.net. And some movies now and then from suprnova. I have stopped using all other p2p software.
To this it should be added that I am big DVD/cinema consumer ever since I started downloading culture.
It is probably different. Swedish laws are sure different than the states (allows for downloading of content and bittorrent trackers, such as Piratebay, is fully legal. So it is not far fetched that slovenian law is also different.:)
USA has not (yet) total control over the world, thankfully.;)
Slashdot Mirror
With my sentence "...orbit where the probe is not affected by the gravitational pull", I ment that there is a gravitational force acting on the probe, but a equal centrifugal force acting in the opposite direction so the sum of the forces is 0. (stable orbit)
:(
In simplified theory the probe can then stay in orbit indefinetly without burning engines, etc, which is what I ment with "not affected by gravitational pull".
However in reality gas-friction, "gravitational waves", tidal energy, other bodies, etc, will remove/add kinetic energy and ultimately destroy the orbit.
My point is that it is not the *weight* that makes the probe do "better" in space than on earth; but rather friction from air or the ground caused by weight and/or size/shape of the probe.
When the probe is in space, the engine is not used to overcome the gravitational force afaik. A traditional rocket places the probe into an appropriate orbit where the probe is not affected by the gravitational pull (all forces equals zero), then the probe use its engine to increase its orbital velocity, and in doing that, increasing the radius of the orbit.
As I said, we have force equilibrium when the engine is not running - that is, the sum of all forces are 0. I am not talking about a vertical "launch", I am just talking about a sort of "horizontal" burn where the engine resides on a frictionless surface of some kind and there is no air. Then the engine should accelerete just as good as it does in space, even though it has "weight".
Say its mass is 1 kg and its weight is 1 million kg and the engine has a 1 N thrust. This means that the acceleration is, using a = f/m is:
1/1 = 1 m/s^2.
That weight of 1 million kg becomes a problem only if we have friction.
I mean that the surface is completely orizontal - that is, the "tunnel" lies in such a way that the probe/engine is not affected at all by gravity (there is no friction, and no air resistance, but the probe does not move until we turn on the engine). Then it would accelerate just as good as it does in space even though it has weight?
>not for e.g. atmospheric flights.
In atmospheric flights you also have problem with air friction.
>you're mixing up mass and weight.
The mass of the probe is the same in a zero-g environment, or on jupiter - it is the weight that is different, we both agree on that.
However, I still dont see why weight, in it self, is (always) relevant for the acceleration of the probe. When we calculate the resulting acceleration from the engines we only consider the mass of the probe and the engine thrust. Now imagine if we have the probe on earth in a vacuum tube floating on some zero-friction surface or magnetic field (we have force equlibrium). Then if the engine are turned on, they would accelerate the probe as much as they do in empty space even though the probe has weight, right? (now the gravitational force is counteracted by the force of the magneticfield, instead of the centrifugal force in orbit)
Hm, I seem to have written a bit stupid.
What I ment was that the weight has nothing to do with it per se (except that it can cause friction), however, if we remove friction (for example by some imaginary surface, magnetic field, or whatever) and air resistance (perfect vacuum tube) on earth, the ion engine would work just as well here on earth?
I believe you are wrong. The probe is not accelerating perpendicular to earths surface, it is accelerating in an orbit around earth. The force accelerating the probe can be anything, as long as it is more than the tiny deacceleration from friction in the thin gascloud that surrounds earth.
When a probe is in orbit around earth no force is required to eliminate the pull of gravity from earth, since this force is counteracted by the centrifugal force due to the circular motion around earth, and the probe stays in orbit (if we assume the friction from the gas in space is zero).
Using the formula you provided for gravitational force, and the formula for centrifugal force, you can calculate the necessary speed you must have to sustain a specific orbit, or virce versa. If you want to leave earth, you just simply have to increase your speed and this acceleration can be how big or small as you like.
And in soviet/russia they have been using ion engines for decades.
;)
Aha, I get it, it is the *commercial* part that is the big thing here, truly revolutionary, eh?
I dont understand why they talk about the probe being (near) weightless in space in the same context as the engine beeing useful in space?
No matter where the probe is, it has got the same mass, and hence the same inertia. Low-thrust engines work good in space because of no friction and often no requirement on quick travel (if it is a non-manned spacecraft). On earth an ion engine would never work for several reasons, one beeing friction against air and ground, but none of them has to do with the weight of the vechile/probe?
Or have I misunderstood something?
The internet got substantially more data than that. Heck, only my ultra small hobby-company has around 1 TB on the internet. And privatly I have around 0.5 TB shared over the internet from home. Then add all other small hobby companies, billions of webpages, colocation-servers, communities, p2p-"seeders" etc etc, and it will quickly pass 230 TB data, many thousand times over.
I must say I agree with you. When I was a kid (which was not too long ago) I always got the prepackaged models and built the car or crane or whatever, and then sooner or later I would dismantle the model to use the parts for something more fun. Building a model from a schematic, following instructions correctly is educational, fun and can learn a great deal on how to build sturdy and stable lego constructions.
:), I think there is no problem with model-packages.
:) would be the various mindstorms robotics invention kits. :)
So as long as the kids gets several packages during the years (so they have lots of pieces
I guess the dream-package for many older kids (and adults
Well, I just think it is pretty obvious that they should have some kind of union, especially when something like this happends (that must have happend several times before).
I think the employees of EA/other programmers/game devs are stupid that they have not formed their own union and made union agreements with their employers. That would increase job security and give the employees a fair share of company profits, etc.
Yeah, I was a bit ironic/sarcastic. Where I live it is natural that all workers are connected to some kind of union (I believe more than 90% of the employees here are connected to some kind of union, and this includes management).
I cannot understand why it is not as common in the states? Why does unions have so bad reputation in the states?
LEGO! I always got LEGO for christmas, and I loved it - and I bet the kids today also love LEGO.
:) (this can be a great gift for adults too.. :)
A tip: Buy the LEGO robot invention kit, and let the kids teach themselves both basics of engineering and programming while having lots of fun!
The workers union for the EA employees must be really angry. Why does they not strike and demand higer pay and/or a more humane work situation?
The problem is not a big government. The problem is bad democracy. The government is supposed to represent the will of the majority - not the rich elite (or "base") ; as is the current situation in USA.
Is it possible to get the raw stream from this card, and then decrypt in software?
And thats where the kyoto agreement comes into picture.. It is therefor important that all/most of the countries can agree on pollution control measures to avoid companies moving in one direction or another.
1) You can probably not play online until the official retail date even with the retail version. So there is ABSOLUTELY no reason at all to by the game for 270 USD instead of downloading a copy from www.piratebay.org, and then purchase the retail version when it is officially available.
:)
2) You are right on this one oth.
Ah, I see.
:)
In Sweden, where piratebay is located, a BBS-related lawsuit years ago concluded that the BBS-administrator/owner could not be held responsible for "warez"/illegal-stuff traded on the BBS by the users of the BBS. The same is argued to be true for a torrent tracker. The tracker is simply viewed as the means by which you can share digital material to others. Now if the material is shared without the copyright holders permission, the responsibility lies with the uploaders and not the tracker administrators.
Furtheron, as everyone knows, no actual copyrighted data is transmitted through the tracker, so I guess it should be even more legitimate than a warez-BBS.
I sure do hope that everyone in my generation (born in the eighties and later) have realized that there simply are no "bad" words.
"Bad" words is a relic of religion and misplaced moral thinking, which has no place in the 21 century. I hope that we all will simply tell our children that there are no bad words and that they can say whatever they want. Afterall, the words they will be using is probably words you are using yourself anyways. I cannot understand why many parents think it is okay that they say "bad" words and at the same time think it is absolutely not okay when their kids does the same thing..
The Piratebay has a torrent that works.
The Piratebay has one, and this will defenitly not go down, like the other torrents.
.torrent file)
(not direct link, press the link, and then download the
I download lots of tvshows, maybe 5-6/week, from http://www.tvtorrents.net. And some movies now and then from suprnova. I have stopped using all other p2p software.
To this it should be added that I am big DVD/cinema consumer ever since I started downloading culture.
It is probably different. Swedish laws are sure different than the states (allows for downloading of content and bittorrent trackers, such as Piratebay, is fully legal. So it is not far fetched that slovenian law is also different. :)
;)
USA has not (yet) total control over the world, thankfully.