People on skateboards.

Yes, retard; 50kg of expanding mass, all expanding against THE MASS THAT CANNOT BE NAMED!!!

What's pushing that 50 kg of mass out the back of the rocket?

Quote from: Papa Legba on October 09, 2015, 01:14:18 PM

Yes, retard; 50kg of expanding mass, all expanding against THE MASS THAT CANNOT BE NAMED!!!

What's pushing that 50 kg of mass out the back of the rocket?

The next 50kg that was just burnt (and is expanding) in the combustion chamber?

Quote from: markjo on October 09, 2015, 01:26:16 PM

Quote from: Papa Legba on October 09, 2015, 01:14:18 PM

Yes, retard; 50kg of expanding mass, all expanding against THE MASS THAT CANNOT BE NAMED!!!

What's pushing that 50 kg of mass out the back of the rocket?

The next 50kg that was just burnt (and is expanding) in the combustion chamber?

Very good.  Now, do you suppose that those burnt and expanding gasses in the combustion chamber are pushing on anything besides the gasses that are being pushed out of the back of the rocket?

Now, do you suppose that those burnt and expanding gasses in the combustion chamber are pushing on anything besides the gasses that are being pushed out of the back of the rocket?

*Yawn!*

Yes, yes, 28,000 posts-of-fail Humpty Dumpty; we are all conversant with your wacky theory that a rocket can somehow create a Reaction against its own Action, thus being able to somehow 'push on itself' (lol!)...

It is as stupid & illogical now as it ever was.

Read this again, carefully, & rebut it rationally please:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.[/b]

No maths required.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

I think that I may see the source of your confusion.  The gunpowder is not just expanding, it's burning.  The process of burning the gunpowder produces energy and combustion gasses, doesn't it?  Those gasses have mass, don't they?

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No.  We have burning fuel which, like burning gunpowder, produces energy (P) and combustion gasses (B).  The energy is what pushes the gasses one way (action) and the rocket the other way (reaction).

No object B, see?

Yes, there is an object B is the gasses produced by burning the fuel A.  Why is that so hard for you to comprehend?

Thus, you have removed the necessary recoil mass required to produce motion.

No, we haven't.  You're just too blind to see it.

But we know a rocket DOES produce motion, don't we?

Of course we do.  You just don't understand how is all.

Ergo, some other mass MUST be taking the place of object B.

Yes, the combustion gasses that are the result of burning fuel.

& the ONLY possibility for that other mass is the Atmosphere.

False dichotomy.  Your refusal to see other possibilities doesn't mean that they don't exist.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Incorrect conclusion from a faulty premise.

Q.E.D.

Yes, you have quite easily demonstrated that you don't have any idea of what you're talking about.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

Then it's a good thing that we never claimed that you could.

No maths required.

For once, I agree.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

Anyone who doesn't understand that the energy from burning fuel is what causes exhaust gasses to expand shouldn't lecture people about how rockets do or don't work.

I think that I may see the source of your confusion. 

You think wrong, shitposting Thought-Policeman; nothing you say ever clarifies matters.

It is not your purpose here to speak Clear Truths; every neutral knows that & despises you for it.

Nothing can create a Reaction against its own Action, nor can anything Push on Nothing.

A child knows this; so what kind of man are you that argues in favour of such Filth-begotten Lies?

Let's get something straightened out before we proceed; your pal frenat is absolutely adamant that a rocket is an open system.

Well; is it?

Is frenat right or wrong?

Let's watch you animals feed upon each other a while, eh?

Should be LOL!

It actually can be considered both open or closed, depending on how you look at it.  But I wouldn't expect you to understand.

during the reaction with the fuel, the forces are internal to the system.  No external forces apply.  That is a closed system. 

After the reaction those hot gasses leave the system.  From that point of view it is open. 

In this case it is described as closed because there are no external forces.  But it definitely loses heat and mass so it is also not adiabatic.

But again, I wouldn't expect you to understand.  That would require an effort on your part.  Far easier to just deny and call someone you don't agree with a troll, right?

But thanks for the humor!

Quote from: markjo on October 10, 2015, 10:12:18 AM

I think that I may see the source of your confusion. 

You think wrong, shitposting Thought-Policeman; nothing you say ever clarifies matters.

It is not your purpose here to speak Clear Truths; every neutral knows that & despises you for it.

Why would neutrals despise me?  I'm not the one who is calling every member of the mainstream physics community a liar and a criminal.

Nothing can create a Reaction against its own Action, nor can anything Push on Nothing.

When did I say that it could?  I'm saying that the energy released by the burning fuel is causing the combustion gasses to push against the rocket (action) and the rocket to push back (reaction).  How can I possibly make that any more clear?

It actually can be considered both open or closed, depending on how you look at it. 

LULZ!!!

I'm saying that the energy released by the burning fuel is causing the combustion gasses to push against the rocket (action) and the rocket to push back (reaction).  How can I possibly make that any more clear?

MORE LULZ!!!

Rockets are both open AND closed systems...

Rockets push on themselves...

Rockets push on nothing ...

Words mean what Humpty Dumpty wants them to mean...

You guys are too much.

Oh, look!

closed system and adiabatic, of which a rocket is neither.

Compare this to:

It actually can be considered both open or closed, depending on how you look at it. 

Is obvious Troll obvious enough yet?

Or do you cultists wish to shit on your own doorsteps even further by defending such a compulsive Liar?

Whatever; let's stick to the point!

None of you have rebutted this logically yet...

Read again, carefully, & rebut  rationally please:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.[/b]

No maths required.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

Oh, look!

Quote from: frenat on October 02, 2015, 02:35:47 PM

closed system and adiabatic, of which a rocket is neither.

Compare this to:

Quote from: frenat on October 10, 2015, 11:18:38 AM

It actually can be considered both open or closed, depending on how you look at it. 

Is obvious Troll obvious enough yet?

Troll defined here as: not conforming to any of the known definitions but rather "someone who disagrees with me so I'll throw some insults around to make myself feel better"

I should have put money down on that fact that you wouldn't even try to understand.  You're so predictable.

Or do you cultists wish to shit on your own doorsteps even further by defending such a compulsive Liar?

Liar defined here as: someone I can't point to actually lying at any time but again I'll throw some insults around to feel better about myself. 

Whatever; let's stick to the point!

You have one?  That'll be a first.

Rockets push on themselves...

Rockets push on nothing ...

Words mean what Humpty Dumpty wants them to mean...

You guys are too much.

Us?  You're the one who thinks that a rocket is the same thing as it's exhaust.  Talk about twisting words to mean what you want. 

Yeah; like I thought - no answers, just desperate group-think shitposts...

Let's try again:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No maths required.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

Yeah; like I thought - no answers, just desperate group-think shitposts...

Let's try again:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No matter how many times you try it, you're still wrong.  The propellant is not just expanding, it's burning.  Do you understand the concept of burning?  You pump fuel and oxidizer (part of object A) into a combustion chamber (another part of object A) and add enough heat to start a self-sustaining chemical reaction that releases a great deal of energy (P) which pushes the resultant exhaust gasses (object B) one way (action) and the rocket (object A) the other way. 

So you see, combustion pushing the exhaust gasses one way (action) and the walls of the combustion chamber the other way (reaction).

Q.E.D.

Now please explain why you keep ignoring the part where the process of burning propellant creates the expanding exhaust gasses.

Blah.  Blah.  Denial.  Blah.

shitposts...

Of which you are the master.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

LMAO, you still don't understand how a rocket works.

Yeah; like I thought - no answers, just desperate group-think shitposts...

Let's try again:

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No maths required.

Anyone who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

For the time being, dealing with how a rocket is propelled within the atmosphere, I will make a statement which I would like you to answer with a 'agree' or 'disagree' response.


'When 500kg of rocket fuel is burnt within the combustion chamber, it is ejected out of the engine nozzles as high speed exhaust particles weighing 500kg.'


If you disagree with the above statement, would you please explain what is wrong with it?

"No one wants to provide an equation?"
You are joking!  For that you need mathematics.  That was used by Galileo, Johannes Kepler, Newton, etc to come up with gravity and the heliocentric system.  Can't trust equations!

Equations are the ONLY thing you can TRULY trust in the world. Noone can manipulate the mechanics of math (1+1=2, no matter what anyone says) and if you believe the equations were somehow manipulated to work using fake mechanics and phenomenons, and describing reality, you should be able to do so yourselves, and I will believe it if it works with reality. And since you will use "real" mechanics and phenomenons your equations should work even better with greater accuracy.

Master_Evar you quoted me:
<"No one wants to provide an equation?"
You are joking!  For that you need mathematics.  That was used by Galileo, Johannes Kepler, Newton, etc to come up with gravity and the heliocentric system.  Can't trust equations!>

Yes. I made that statement, but I was trying be satirical and say what I thought might be a response from certain flat earthers.  My jokes usually fall flat!  Probably as a result of trying to crack jokes to Engineering students for 35 years or so.  What would I know about equations and Newton's Laws?

Master_Evar you quoted me:
<"No one wants to provide an equation?"
You are joking!  For that you need mathematics.  That was used by Galileo, Johannes Kepler, Newton, etc to come up with gravity and the heliocentric system.  Can't trust equations!>

Yes. I made that statement, but I was trying be satirical and say what I thought might be a response from certain flat earthers.  My jokes usually fall flat!  Probably as a result of trying to crack jokes to Engineering students for 35 years or so.  What would I know about equations and Newton's Laws?

Ahh, I see.

Engines that propel rockets by means of the rearward discharge of a jet of fluid, usually hot exhaust gases generated by burning fuel with oxygen, the only practical means of propulsion so far devised is to take advantage of Newton's third law of motion. In its simplest form, this law states that action and reaction are equal and opposite. It is observed in nature that forces (e.g., pushes or pulls) never occur singly but always in equal or opposite pairs. Thus the existence of a force on a body requires the coexistence of an equal and opposite force. If a pair of forces acts between two separate bodies (and provided that no other forces act), the bodies will be impelled to separate or come together depending on whether the force pair is repulsive (a push) or attractive (a pull). The combination of Newton's second and third laws shows that the resulting motion of the two bodies can be expressed by the statement that the change in momentum of the two bodies is equal and opposite and along the line of action of the force pair. Momentum is the product of mass and velocity, and, because (at rocket velocities) the mass of any body remains constant, a force pair acting between two bodies produces a change in the velocity of each. It is clear that in order to propel a body it is necessary to find something to push against. All rocket propulsion devices push against the air itself. If the exhaust is used as the propelling medium, it must experience a change in momentum i.e., it has to be accelerated toward the rear of the rocket and discharged rearward with enough velocity that the reaction produces an appreciable thrust in the opposite direction.

You pump fuel and oxidizer (part of object A) into a combustion chamber (another part of object A) and add enough heat to start a self-sustaining chemical reaction that releases a great deal of energy (P) which pushes the resultant exhaust gasses (object B) one way (action) and the rocket (object A) the other way. 

LOL!!!

A dunce's cap & extra homework for shitposting sock-puppet meister markjo.

Let's try again, retards...

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No maths required.

Anyone else who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Let's try this step by step, starting with a few simple yes/no questions, if you think you can handle them.

1) Does the "expanding" propellant burn?

2) If yes, then does the process of burning the propellant produce exhaust gasses with roughly the same mass as the propellant being burned?

3) If yes, are the exhaust gasses the same object as the propellant before it's burned?

The Dunce puts the Cap on & sits in the corner.

The Dunce sits in the Corner & does its Homework.

Ok, Humpty Dumpty Dunce markjo?

markjo, You have to realize that if your rocket made it to space by pushing on the exhaust, as soon as it gets there the vacuum of space is going to suck every exhaust molecule away from the rocket leaving nothing to push against anymore. You can't see that happening?

The Dunce puts the Cap on & sits in the corner.

The Dunce sits in the Corner & does its Homework.

Ok, Humpty Dumpty Dunce markjo?

I am happy sit in the Corner doing my homework with the help of my GPS using its access to 48 satellites (24 GPS and 24 GLONASS).

Of course these were inserted into orbit using rockets.  I would not dare claim that it is really a "vacuum" up there! 
If the most knowledgeable person in the world (AKA TheEngineer, Engy, Engy Baby, Douchbag) were to read this he might argue that it's not "really a vacuum" up there - there are a few molecules scattered about, true but even that great "self made man, who worshipeth his maker" would not argue that it was significant!

Anyone who claims that rockets do not work in a vacuum has rocks in their head (In Oz we would say a few roos short in the top paddock).  Do you really think that the 239,725 kg (empty) of Apollo 11 was lifted by pushing on the ground then the air?  The ground helps very little as the exhaust is ejected out the side.  Of course these figures come from NASA and you will say that Apollo 11 was just a lifesized cardboard replica!

Maybe the burnt fuel (1,965,969 kg) liquid oxygen, 651,210 kg kerosene and 92,205 kg liquid hydrogen) ejected provided a bit of reaction mass.  If not what happened to the momentum of that 2,709,384 kg - burnt up I supposed?  But then you don't really trust Newton do you?

Get used to it - rockets work better in a vacuum - less resistance!

It's not really too difficult to grasp it you try - "it's not rocket science" - oops, my bad, it is!

markjo, I do hope you don't mind being stuck in this corner with me - I can be a bit of a bore!

The Dunce puts the Cap on & sits in the corner.

The Dunce sits in the Corner & does its Homework.

Ok, Humpty Dumpty Dunce markjo?

Okay, so you're unable or unwilling to answer some very simple questions.  Please let me know when you're ready to have and adult conversation.

markjo, You have to realize that if your rocket made it to space by pushing on the exhaust, as soon as it gets there the vacuum of space is going to suck every exhaust molecule away from the rocket leaving nothing to push against anymore. You can't see that happening?

No, because that isn't how rocket engines work.  Free expansion only works as fast as the gas molecules can travel on their own.  The gasses in a rocket's combustion chamber can exit through the throat of the engine several times faster than the speed of sound (as seen in the shock diamonds in the shuttle main engine).  The exhaust gasses aren't getting sucked out, they're being forced out, so free expansion does not apply.  Or at least not until the gasses clear the engine bell, at which point they no longer interact with the rocket and are therefore irrelevant.

Please let me know when you're ready to have and adult conversation.

Please let me know when you've learnt to spell a simple word like 'an', Dunce.

Now; the Dunce will put its cap on & sit in the corner.

The Dunce will sit in the corner & do its Homework.

The Dunce will be ignored until it learns that an object cannot create a Reaction off its own Action.

The Dunce will be ignored until it learns that YOU CANNOT PUSH ON NOTHING.

Okay, ever-so-adult Humpty Dumpty markjo? 

Quote from: markjo on October 13, 2015, 07:19:18 PM

Please let me know when you're ready to have and adult conversation.

The Dunce will sit in the corner & do its Homework.
The Dunce will be ignored until it learns that an object cannot create a Reaction off its own Action.
The Dunce will be ignored until it learns that YOU CANNOT PUSH ON NOTHING.
Okay, ever-so-adult Humpty Dumpty markjo?

Apollo 11 along with the Saturn 5 weighed 239,725 kg empty.  Its fuel load was 1,965,969 kg liquid oxygen, 51,210 kg kerosene and 92,205 kg liquid hydrogen - a total of 2,709,384 kg.

Just what do you think happens to the momentum of that almost 3000 tons of propellant ejected at supersonic velocity!  Burning it does not change its mass, but its volume and hence velocity on exit is increased tremendously.  The fuel in the vehicle has relatively little momentum, so there is large change in momentum as it is burnt and ejected.  force = rate of change of momentum - hence big force - 7.5 million pounds of thrust at liftoff, about 3750 US tons.

You say YOU CANNOT PUSH ON NOTHING.  That propellant IS the reaction mass.  What is the difference between a bullet ejected from a gun and gas ejected from a rocket - they both have mass and they are both ejected at high speed.  They both provide thrust: recoil in the gun's case, thrust for lift in the case of the rocket.

Maybe you get some knowledgeable engineer to explain it better?  There are probably a few of those among the members.

What is the difference between a bullet ejected from a gun and gas ejected from a rocket

I already explained this: look!

With a gun you have object A, the mass of the gun; the expanding propellant, P, the gunpowder, sited between them; and object B, the mass of the bullet.

But with a rocket you ONLY have object A, the mass of the rocket,  & the expanding propellant, P, the fuel.

No object B, see?

Thus, you have removed the necessary recoil mass required to produce motion.

But we know a rocket DOES produce motion, don't we?

Ergo, some other mass MUST be taking the place of object B.

& the ONLY possibility for that other mass is the Atmosphere.

Ergo, NO atmosphere, NO motion; rockets CANNOT function in a vacuum.

Q.E.D.

No matter how hard you try to spin it, cultists, every child knows that You cannot Push on Nothing.

No maths required.

Anyone else who says the exhaust  (which clearly represents P, the expanding propellant) is object B must put on a dunce's cap & sit in the corner until they've done their homework correctly.

So, slow-learner rabinoz; you too can join markjo in the corner, wearing a Dunce Cap & doing your homework.

Yendor, do you even know what free expansion means? Because if you do you'll understand why it is irrelevant to the topic of the thread.

A vacuum does not suck. But high pressure gases push. The molecules in the high pressure exhaust gas pushes other molecules in it. The molecules at the nozzle get's pushed away from the ship in a vacuum, because there is nothing to push it back.  The molecules that pushed those molecules had to be pushed themselves, which was done by other molecules further inside the combustion chamber. And those molecules was pushed by other molecules even further in. And the furthest in the molecules is pushed by the wall of the combustion chamber, which happens to be part of the rocket. And because of Newton's third, the molecules pushes back on the walls of the combustion chamber with an equal force. No atmosphere is needed.