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by paul
12/07/19 03:58 AM
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#34925 - 06/12/10 04:52 AM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
-Unless acted upon by a net external force, a body, at rest, will remain at rest and a body, in motion, will remain in motion.


the pipe is itself a body.
if you are or are not capable of understanding that is your problem.

I have clearly shown all the possible forces involved and according to the forces
WHICH IS WHAT THE LAWS ARE ABOUT.

the pipe will move just as I described.

your clinging to your STUPID EXCUSSES with missinterpreted laws will do you no good.


BTW , I do agree that momentum is conserved also.

there is clear conservation occurring between the pipe and the weights.

the force that propels the weights is divided between the pipe and the weights.

the momentum is also divided between the pipe and the weights.

I cant help it if you cant understand that , its exactly what would happen in this situation
in zero g.






_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34926 - 06/12/10 05:39 AM Re: Orion, Mission to Alpha Centauri [Re: kallog]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
All speeds measured relative to the pipe.
1. Railgun accelerates a 20kg mass up to 1m/s
2-10. Same again for other masses
11. Other railgun decelerates the first mass to 0.
12-20. Same again for other masses
21. Same railgun accelerates the first mass to -1m/s.
22-30. Same again for other masses

???

Railguns have reaction forces pushing the pipe the opposite way. I didn't see that mentioned in your post.

well duhhh , thats the reason the pipe moves.

your little 1-30 above is not very well though out.

Quote:
1. Railgun accelerates a 20kg mass up to 1m/s


thats 100 kg and 5 m/s
Im ammased you missed that.
ie....
if each weight weighs 100 kg
and each weight has a velocity of .5 m/s
to find the force needed to achieve the .5 m/s velocity.

F = m*v
F = 100 kg / .5 m/s = 50 kgf
--------------------------------------------------------
Quote:
2-10. Same again for other masses

I suppose your are talking about the weights in the turnarounds.

and if for some stupid reason you are sudgesting that one weight is decelerated
while another is accelerated , you are wrong.
Quote:
11. Other railgun decelerates the first mass to 0.

nope , the other rail gun is only used to stop and hold the weights in place.
and to slightly accelerate the weights.

Im not sure that you read the post , because from your assesment it does not appear that way.
--------------------------------------------------------
Quote:
11. Other railgun decelerates the first mass to 0.

wrong again , you should take a word comprehension refresher course.
I said that the other rail gun is used to stop or hold the weights.
not to decelerate the weights at the same time as the other weights are accelerating.
its pretty easy to see what I wrote.

--------------------------------------------------------
Quote:
12-20. Same again for other masses

nope the opposing weights are floating.

--------------------------------------------------------
Quote:
21. Same railgun accelerates the first mass to -1m/s.

wrong again.

--------------------------------------------------------

its pretty clear to me that neither of you have much mechanical sence
about you.

Quote:
a = 500 kgf / 500 kg

Ouch. This horrible bastardization of units is why it's easy for me to stop bothering to follow. Sure you're probably correct but there's certainly simpler ways to do it. What on earth does a kgf have to do with a machine floating in space? There's no Earth gravity, no weight of a kg up there. Please use consistent units. Even imperial ones, as long as they satisfy equations like F=ma and v=d/t. Your above equation subtly has acceleration in units of g.


that is terrible isnt it , its exactly how it works in zero g.

notice I did not include resistance.

a mass in space is the same as a mass on earth , only you can push it
with less force because there is zero resistance to movement in zero g.

the only difference betweem a mass on earth and a mass in zero g is
gravity.

it still has the same mass.
so it requires the same force.

do you think you can push a 100 kg mass on earth with a 1 kg force.

no because you have to first overcome the inertia of the mass to get it to
start moving.

because of the resistance.

no such bastardization in zero g , sorry mr know it all.

your wrong again.











_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34927 - 06/12/10 07:21 AM Re: Orion, Mission to Alpha Centauri [Re: paul]
kallog Offline
Megastar

Registered: 03/17/10
Posts: 1100
Originally Posted By: paul
your little 1-30 above is not very well though out.

As I said, I didn't bother to follow your complicated working. That was an example of how I'd like you to describe it so it's easy to see. You're asking me to do a lot of work to figure it out, including correcting mistakes along the way. Why not put more effort in yourself? Before guessing an equation, look it up in a text book or on Wikipedia. It's also much easier to do everything with symbols and no numbers.


Quote:

thats 100 kg and 5 m/s
Im ammased you missed that.

As I said, I didn't bother to follow your complicated working.

Quote:

and if for some stupid reason you are sudgesting that one weight is decelerated
while another is accelerated , you are wrong.

As I said, I didn't bother to follow your complicated working.


Quote:

Im not sure that you read the post , because from your assesment it does not appear that way.

As I said, I didn't bother to follow your complicated working.


Quote:

do you think you can push a 100 kg mass on earth with a 1 kg force.

Despite your insults, it's clear you haven't got the faintest idea about mechanics. That's especially easy for a boat floating on calm water, where friction goes towards zero at low speed.


Quote:

no such bastardization in zero g , sorry mr know it all.

your wrong again.

Paul, I've put up with your ongoing insults for a long time. I usually quietly ignore them, but it's getting a bit too much. Please behave more courteously. I'm sure you understand that insults don't make people understand you, rather they polarize people against you.

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#34928 - 06/12/10 08:11 AM Re: Orion, Mission to Alpha Centauri [Re: kallog]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Kallog

you and byran can discuss this between yourselves , Im sure that
between the two of you ,you can arrive at a completely asinine
conclussion.

and as for insults , just reading your post is insulting.

you two come on like your the smartest people in the world but
underneath the facade the only thing I see is two people who
seem inteligent but have a extreme lack of cognitive powers.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34931 - 06/12/10 04:29 PM Re: Orion, Mission to Alpha Centauri [Re: paul]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Originally Posted By: kallog
As I said, I didn't bother to follow your complicated working.


So its normal for you to just simply state your uninformed opinion
on subject matter.
even if you havent read the information presented , you automatically
follow with your opinion of the information that you havent read.

Originally Posted By: paul
do you think you can push a 100 kg mass on earth with a 1 kg force.


Originally Posted By: kallog
Despite your insults, it's clear you haven't got the faintest idea about mechanics. That's especially easy for a boat floating on calm water, where friction goes towards zero at low speed.


given that I was refering to the frictionless environment of zero g
what you posted has pretty much confirmed my assessment of your cognitive abilities
and your mechanical abilities including your knowledge of mechanics.

you used a boat in water -- low friction -- when I was refering to a mass
sitting on the ground -- on earth.

ie...the resistance to movement of a object sitting on earth due to gravity.

Originally Posted By: paul
notice I did not include resistance.

a mass in space is the same as a mass on earth , only you can push it
with less force because there is zero resistance to movement in zero g.

the only difference between a mass on earth and a mass in zero g is
gravity.

it still has the same mass.
so it requires the same force.

do you think you can push a 100 kg mass on earth with a 1 kg force.



I suppose you read the last line of what I posted above and constructed
your anology from that single line.
as you have already informed us that you dont fully read information you
just breeze through it.

Brilliant not even slightly smart , and common among naysayers.










_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34932 - 06/12/10 05:21 PM Re: Orion, Mission to Alpha Centauri [Re: kallog]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
one more thing that I would like to tell the others that are
following this thread.

at any given time durring acceleration of the pipe.

1) there are 20 masses being accelerated.

being accelerated means that a opposite force is being placed
on the pipe that will give acceleration to the pipe.

2) the opposing 20 masses are not being accelerated.

nor are they decelerating.

3) the forces of the two masses that are being turned around by the tubes (2) 180 degree turnarounds will cancel each other out.

conclusion:

at any moment durring the acceleration of the 20 masses there is a force being placed on the pipe in a direction.

at any moment durring the acceleration of the masses there
are no counter forces being placed on the pipe that could
prevent the pipe from accelerating.

therefore the pipe will accelerate in a direction.

a = F/m

---------------------------------------------------------

thats pretty much as clear as I can put it.
and its simple enought for a grade school student to understand.

if the two seemingly highly intelligent naysayers that have
been involved in this discussion with me dont realize this
then that only shows that their ability to process information
has been flawed or never was there.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34937 - 06/12/10 07:15 PM Re: Orion, Mission to Alpha Centauri [Re: paul]
ImagingGeek Offline
Senior Member

Registered: 05/19/10
Posts: 410
Loc: Canada
Originally Posted By: paul
Quote:
-Unless acted upon by a net external force, a body, at rest, will remain at rest and a body, in motion, will remain in motion.


the pipe is itself a body.
if you are or are not capable of understanding that is your problem.


We all agree it is a body - but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal

Originally Posted By: paul
I have clearly shown all the possible forces involved and according to the forces


No, you've steadfastly ignored newtons laws, in particular newtons 3rd law.

Bryan
_________________________
UAA...CAUGCUAUGAUGGAACGAACAAUUAUGGAA

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#34939 - 06/12/10 07:37 PM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


it doesnt matter where the force comes from , if it comes from inside the pipe or outside the pipe.
its pretty stupid of you to think that it does.

below I have underlined the word "you" so that
others wont get the opinion that "I" have the same understanding as bryan who just happens to be the "you"
below.

if you were sitting inside a large can on earth
that is completely sealed.

then the large can suddenly was in deep space.

and you stood up inside the can.

according to your understanding of physics the large can would not move as you stand.

I say the large can moves away from you , because of the force that you applied to the large can while standing , and smashes into your head.


if you were outside on the top of the large can and stood up the large can would move according to your understanding of physics.

I say the large can moves away from you , because of the force that you applied to the large can while standing.


you cant just have it your way , bryan.

its basic physics , rock bottom physics , grade school physics.


now I suppose you will reply once again saying that the large can would move as you have repeatedly done in the past , contridicting yourself once again and sinking further into the mire that you created for yourself.


Quote:
No, you've steadfastly ignored newtons laws, in particular newtons 3rd law.



you are the one who is ignoring newtons laws , bryan.

you are ignoring #1 #2 and #3 of newtons laws of motion.

by insisting the pipe would not move.
you try to use newtons laws but they are flawless and
cannot be used to support your missinterpretations of them.

Quote:
but note you need an external force.


no I dont , you do , I know better.

_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34940 - 06/12/10 08:43 PM Re: Orion, Mission to Alpha Centauri [Re: paul]
ImagingGeek Offline
Senior Member

Registered: 05/19/10
Posts: 410
Loc: Canada
Originally Posted By: paul
Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


it doesnt matter where the force comes from , if it comes from inside the pipe or outside the pipe.
its pretty stupid of you to think that it does.


LOL, this from a guy whose continually shown a complete ignorer of newtons laws, and who thinks homeopathy is anything but a scam.

Internal forces are always balanced - equal and opposite as per newtons 3rd law. Ergo, external forces or the ability to impinge a force on the external environment are an absolute requirement for changes in momentum.


Originally Posted By: paul

if you were sitting inside a large trash can on earth
that is completely sealed.

then the trash can suddenly was in deep space.

and you stood up inside the can.

according to your understanding of physics the trash can would not move as you stand.


Nope, that is not what I said, not even close.

A trash can is open - I'd knock the lid off and fly out the top; the trash can would go the other way with equal momentum.

But if the trashcan was sealed, and large enough for me to stand, then when I stand the can would go one way, I the other. When I hit the top of the can the resulting force would cease all of the movement. End effect - can shifted one way, myself shifted the other, but the net center of mass exactly where it was when I started and the total momentum unchanged.

Originally Posted By: paul

I say the can moves away from you , because of the force that you applied to the can while standing.


But in the case you describe, the can is an open system - exactly what kellog and I have been telling you is needed since day 1.

If the lid were welded on - i.e. the trash-can equivalent of your pipe - the can wouldn't go anywhere. No changes in momentum are possible without external forces.

Bryan
_________________________
UAA...CAUGCUAUGAUGGAACGAACAAUUAUGGAA

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#34944 - 06/12/10 09:00 PM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
you said
Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal

I said
Quote:
now I suppose you will reply once again saying that the large can would move as you have repeatedly done in the past , contridicting yourself once again and sinking further into the mire that you created for yourself.

you said
Quote:
But if the trashcan was sealed, and large enough for me to stand, then when I stand the can would go one way,

I said
Quote:
if you were sitting inside a large can on earth
that is completely sealed.


you said
Quote:
But in the case you describe, the can is an open system - exactly what kellog and I have been telling you is needed since day 1.


so completely sealed actually means open , correct.
just like the back of a car is the front of a car , correct.

your really expressing your inteligence , bryan.

so when you are inside the can that means you are outside the can , am I following your pattern of thought corectly , bryan?

ie .. is internal actually external , bryan.


you said

Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


is this how you can have it both ways , bryan.

by simply reversing the meanings of words.

is this what happened to newtons laws , add a little here
subtract a little there , reverse a meaning here and there.

soon you will have it just the way you want it , correct.







_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34946 - 06/12/10 11:24 PM Re: Orion, Mission to Alpha Centauri [Re: paul]
ImagingGeek Offline
Senior Member

Registered: 05/19/10
Posts: 410
Loc: Canada
Originally Posted By: paul
your really expressing your inteligence , bryan.

LOL. This coming from the guy who had to crop my post to make it say waht he wanted to - I described an open and closed garbage can.

Cropping the closed garbage can doesn't change that reality.

And don't think your attempt to re-write what I said made us miss the fact that you were completely unable to refute, or even comment on, the difference between the open verses closed garbage can...

What's the matter paul, cannot make your "point" without altering what people have said? Or is this just what you do when faced with a simple, logical answer that completely demolishes your "hypothesis"?

Originally Posted By: paul

Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


is this how you can have it both ways , bryan.


Nope paul, had you not dishonestly removed part of my post it all would have been consistent. The fact you'd openly try to distort what I wrote - when its all immediately above your post - speaks volumes about your duplicity.

Internal forces in closed systems - i.e. you jumping around in a sealed garbage can - cannot alter momentum of your inertial frame (i.e you + garbage can). To alter the momentum of your inertial frame you need either:

a) an external force, or

b) an open system, so your internal forces can act on the external environment

As I described in my last post...and opposite of how you tried to re-write what I said.

Originally Posted By: paul

is this what happened to newtons laws , add a little here
subtract a little there , reverse a meaning here and there.


Yeah, that's a fair description of what you did. Removed those inconvenient little bits where the laws say things like "external forces".

Bryan
_________________________
UAA...CAUGCUAUGAUGGAACGAACAAUUAUGGAA

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#34947 - 06/12/10 11:29 PM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
And don't think your attempt to re-write what I said made us miss the fact that you were completely unable to refute, or even comment on, the difference between the open verses closed garbage can...


why should I refute or comment on something that I didnt say?


Quote:
Nope paul, had you not dishonestly removed part of my post it all would have been consistent. The fact you'd openly try to distort what I wrote - when its all immediately above your post - speaks volumes about your duplicity.


I suppose the below is the "cropping you refer to"


Quote:
We all agree it is a body - but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal



and this is the part that I cropped.


Quote:
but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


so this is the part I cropped out of the above

We all agree it is a body -

and I cant see where that would make a big difference anyway.

of course , at least I agree , not so sure if you agree because according to newtons laws a body acted upon by a force will move.

and you have constantly dissagreed with that and so Im not
sure that you agree its a body.

you keep saying the pipe wont move , dont you , should I go back and collect every time you said that?











_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34948 - 06/13/10 12:14 AM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
#34662

1)

Doesn't work that way - material thrown within the ship will encounter resistance with the air, hull, etc. This will generate a force equal to the force of the propellant, thus neutralizing the thrust of the propellant. Its the ol' opposite and equal reaction thingie - the movement of the propellant will "push" on the ship, but the interaction of the propellant with the ship will push back equally. Net effect - zero thrust.

These kinds of internal energy transfer system only work in places where there is friction to counter the unwanted "return" energy of the propellant. Basically, you can thrust in one direction using a lot of force quickly, pushing the object forward. You then recover your propellant slowly, so the force of the propellant moving in the "wrong" direction doesn't exceed the static friction holding you in place.

That doesn't work in space - no friction.

2)

Doesn't work that way, for the reasons mentioned above. In space, the net thrust of this kind of system is zero. And even in places where it is possible, the ISP would suck.

3)

Only if the contents of that hose are free to leave the ship. If they are not, the momentum of the air will be transfered back to the ship, providing a net zero thrust.

4)

Open the system though - eject that air out of the ship itself - and you'll move along quite nicely.

5)

Because that is the problem with your own model. Your space ship is a closed system; matter can neither enter nor leave. You can exert forces within such a system, but the sum of those forces will always be zero at the level of the system itself

the above are from page 2 and 3

I dont want to spend the rest of the night showing you your insistence that the
pipe wont move.


Im certain I can find plenty in the other 13 pages however.

in my personal opinion , I think , I believe that you need
to learn how to assess a situation , and adapt to it , adapt to the changes.





_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34952 - 06/14/10 11:09 AM Re: Orion, Mission to Alpha Centauri [Re: paul]
kallog Offline
Megastar

Registered: 03/17/10
Posts: 1100
Hello again Paul, I've taken a forced leave of absence due to my failure to appreciate a cultural taboo of western society concerning a specific group of 'chosen' people wink But coincidently it seems all you guys suffered a similar fate, so haha :P


Originally Posted By: paul

at any given time durring acceleration of the pipe.

1) there are 20 masses being accelerated.
...
2) the opposing 20 masses are not being accelerated.
...
3) the forces of the two masses that are being turned around by the tubes (2) 180 degree turnarounds will cancel each other out.


Yep that's much clearer, cheers. I think, let me try to reconstruct it, correct me if I'm wrong:

There are 20 masses being accelerated along the length of the pipe. The reaction to this is what accelerates the pipe.

At the same time 20 other masses are free-floating in the opposite direction.

Both sets of masses reach their ends at the same time, where they're both turned around by a 180deg curved track/etc. The reactions from these two turn-arounds cancel each other out.

Repeat indefinately.



Quote:

if the two seemingly highly intelligent naysayers that have

Cheers! Not everyday that somebody finds I seem highly intelligent smile

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#34953 - 06/14/10 11:19 AM Re: Orion, Mission to Alpha Centauri [Re: ImagingGeek]
kallog Offline
Megastar

Registered: 03/17/10
Posts: 1100
Originally Posted By: ImagingGeek

We all agree it is a body - but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal


Careful there! Nature doesn't care if the ladder's bolted to the inside of the tube or to the outside.

It all depends what you define as the 'body'. If you say it's the pipe, then yes, Paul's right, it can be accelerated by things inside it, they're not the pipe, they're other things. You run into problems if you try to move the pipe further than you move the contents tho.

If you define the 'body' as the collection of the pipe and its contents, then conservation of momentum applies to the center of mass of the collection of things.

Well I'm sure you knew that, but getting careless is no way to sort out a disagreement!

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#34955 - 06/14/10 02:04 PM Re: Orion, Mission to Alpha Centauri [Re: kallog]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
There are 20 masses being accelerated along the length of the pipe. The reaction to this is what accelerates the pipe.

Yes , the rail gun is accelerating 20 masses at any given time, and as a result of the force applied to accelerate the 20 masses in one direction , the pipe is accelerating in the opposite direction.
and accelerating 20 masses requires 20 forces.
and these 20 forces cause the pipe to accelerate in the opposite direction according to newtons laws of motion.

Quote:

At the same time 20 other masses are free-floating in the opposite direction.


Yes, because these 20 masses are not being accelerated
they will not counter the acceleration of the 20 masses occuring in the
rail gun.

according to newtons laws of motion.

Quote:

Both sets of masses reach their ends at the same time, where they're both turned around by a 180deg curved track/etc. The reactions from these two turn-arounds cancel each other out.


Since the masses being accelerated will be traveling slightly faster than the masses that are floating the other way , there will be a slight difference in the timming that the individual masses reach the 180 degree turnarounds.

the individual masses that are being accelerated in the rail gun will reach the turnaround slightly faster than the individual masses that are floating to the other turnaround.


Quote:


Repeat indefinately.


Yes , or as long as you need to accelerate the pipe.

so you have a continous force in a single direction
that applies to the pipe causing the pipe to continously accelerate.

according to newtons laws of motion all the above is well within his constraints.

this could be used in a space ship for propulsion.
as long as you have a ample power supply to power the rail guns.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34961 - 06/14/10 08:53 PM Re: Orion, Mission to Alpha Centauri [Re: paul]
Momos Offline
Member

Registered: 01/15/10
Posts: 48
Loc: Germany
It took me quite some time to read all your posts smile
In the end I have to say: paul, you are wrong. The explanations of kallog and ImagingGeek are perspicuous. And have been from the very beginning. Maybe you should cool off some time and carefully read them again.


@ImagingGeek
You wrote some interesting stuff I didn't know, especially about the back-pressure and maximum exhaust speed, thanks!

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#34963 - 06/14/10 10:36 PM Re: Orion, Mission to Alpha Centauri [Re: Momos]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
In the end I have to say: paul, you are wrong.


well , you've said it.
and everybody has a right to their own opinions.

after all your opinion doesnt matter to me , some may value
it , but I dont.

perhaps you have something perspicuous to base your opinion on.
certainly its not a physical law as the concept adheres to
physical laws.

of course if you dont have any input other than just saying
that I am wrong , then no one will have any proof that I
am wrong , including yourself.

until then , I can just say that you dont exist.
therefore I shouldnt concern myself with what you think.

you may have a different opinion on that , but I can
still say it , think it.

and your opinion or my opinion will not decide if the concept is or is not valid.

but my opinion of your opinion is that you are wrong !!




_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#34968 - 06/15/10 03:05 AM Re: Orion, Mission to Alpha Centauri [Re: paul]
kallog Offline
Megastar

Registered: 03/17/10
Posts: 1100
Originally Posted By: paul

the individual masses that are being accelerated in the rail gun will reach the turnaround slightly faster than the individual masses that are floating to the other turnaround.


It's crucial to quantify that in case 'slightly' is actually 'too much'.

- The pipe starts with momentum
pp = 0
- An accelerated mass starts with momentum p1.
- After acceleration at force F for time t it ends up with momentum p1+F*t. The reaction has the opposite effect on the pipe,
pp = 0-F*t
- After turning around 180deg, its momentum in the free-floating stage is -(p1+F*t). This is a change in momentum of -2*(p1+F*t), so the reaction on pipe causes the opposite change in momentum. The pipe gains 2*(p1+F*t),
pp = 0-F*t+2(p1+F*t)
- But at the same time a free-floater is turning around at the other end, imparting momentum -2*p1 onto the pipe.
pp = 0-F*t+2(p1+F*t)-2*p1
Then that just-turned-around free-floater starts to accelerate, imparting -F*t to the pipe during it's travels.
pp = 0-F*t+2(p1+F*t)-2*p1-F*t

There's could also be a slight error because I did everything in the frame of the pipe's initial rest state, but assumed no pipe movement.

This assumption would be valid if the pipe hardly moved at all, say if it had a really huge mass. That's fine, even a huge mass will keep drifting through space given a little momentum.


Edited by kallog (06/15/10 03:12 AM)

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#34975 - 06/15/10 04:32 AM Re: Orion, Mission to Alpha Centauri [Re: kallog]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
your right , and its going to require a program to get the slightly just right.

at least I would rather do it that way to be more precise.

because the 20 masses being accelerated (M1 - M20) will
be moving slower at the starting point of acceleration.
and faster at the ending point of acceleration where they enter the turnarounds.

this will set up a gradient between the turnaround exits and entrances.

I think it would be easier to just let a program do all the calculations from pipe P=0 to desired acceleration.

I could make the program build a text file as it runs the calculations.

and then post the text file.


_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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