It's 2015 and you aren't even close to owning a Spaceship

Quote from: Heiwa on June 17, 2015, 03:40:42 AM

Quote from: Papa Legba on June 17, 2015, 01:49:41 AM

You all agreed the exhaust gases would produce no thrust once past the rim of the nozzle.

Exact - the mass of the exhaust gas is producing the thrust applied on the Spaceship, when leaving the nozzle at high velocity. Afterwards the exhaust gas is just pollution.

Actually in standard hydrogen-oxygen rockets the exaust is just water vapor which is not pollution.

Mikeman, I know you mean well, but once again, you give incorrect information.  Let us say that the fuel used by the rocket is pure hydrogen and oxygen, and the exhaust that is produced is in fact pure water.  Where did the hydrogen come from?  Generally speaking, the hydrogen comes from sending an electric current through water.  So, we start with water and end with water.  This sounds very clean, but where did the electricity come from?  Burning coal maybe?  Solar panels sound very clean, but people do not realize just how much pollutants are generated during their production.  I could go on, but there just are not any real clean ways of producing hydrogen, so your hydrogen rocket polluted something, somewhere, in order to use its fuel.  It is just how things work. 

Rayzor; if, as you state, understanding Newton's 3rd law is a key component in understanding how rockets work, then for you all to keep repeatedly making the same mistake as NASA of claiming that both the forces described by said law are created on the same object shows you do not understand either.

Also, you are very bad at insults; getting a sense of humour may help you in this regard.

This video still shows the law to be true.
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As he releases the ball he moves backwards. The same principle is why water rockets work better with water in them. They need the extra mass of the water leaving to provide more thrust.

Quote from: mikeman7918 on June 17, 2015, 11:34:16 AM

Quote from: Heiwa on June 17, 2015, 03:40:42 AM

Quote from: Papa Legba on June 17, 2015, 01:49:41 AM

You all agreed the exhaust gases would produce no thrust once past the rim of the nozzle.

Exact - the mass of the exhaust gas is producing the thrust applied on the Spaceship, when leaving the nozzle at high velocity. Afterwards the exhaust gas is just pollution.

Actually in standard hydrogen-oxygen rockets the exaust is just water vapor which is not pollution.

Mikeman, I know you mean well, but once again, you give incorrect information.  Let us say that the fuel used by the rocket is pure hydrogen and oxygen, and the exhaust that is produced is in fact pure water.  Where did the hydrogen come from?  Generally speaking, the hydrogen comes from sending an electric current through water.  So, we start with water and end with water.  This sounds very clean, but where did the electricity come from?  Burning coal maybe?  Solar panels sound very clean, but people do not realize just how much pollutants are generated during their production.  I could go on, but there just are not any real clean ways of producing hydrogen, so your hydrogen rocket polluted something, somewhere, in order to use its fuel.  It is just how things work.

You're obviously ignoring the assertion "Afterwards the exhaust gas is just pollution" which drew the response "the [exhaust] is just water vapor which is not pollution." Whether the process used to generate the fuel was a source of pollution was not in the scope of the assertion, which was only concerned with whether the exhaust gas itself was pollution after the fuel is burned (do you see the word "afterwards" in there now?)

Nice try at diversion, but please try to stick to the actual discussion, or maybe start a new thread. If you don't really understand what's being discussed, then maybe not saying anything at all would be best. Thanks!

Rayzor; if, as you state, understanding Newton's 3rd law is a key component in understanding how rockets work, then for you all to keep repeatedly making the same mistake as NASA of claiming that both the forces described by said law are created on the same object shows you do not understand either.

Also, you are very bad at insults; getting a sense of humour may help you in this regard.

I can't help it if you don't understand Newtons Laws,  Get youself a high school physics text book and do some homework.   I don't think I've been insulting,  unless you regard being called a wannabee conspiracist an insult.

Sokarul: Ah! The good old 'man-on-skateboard' false analogy!

We haven't had a false analogy for a while, & I already debunked this example once on this thread; but as you clearly have not read, or not understood, my post then I will repeat it...

Special for you, like!

So; according to NASA, the skateboard represents the rocket, the man represents the engine & the ball represents the rocket exhaust.

This is false.

In fact, it is the man's arm, in thrusting upon the ball, that represents the exhaust, whilst the ball represents an outside mass that the exhaust thrusts upon.

You see what they did there?

Thus, the man on the skateboard represents Object A, the ball represents Object B, & the requirements of Newton's 3rd law are fulfilled.

Rayzor; I don't care if you think I understand Newton's 3rd or not; your behaviour today has confirmed to any neutral reader that nothing you say is worthy of being taken seriously.

Sokarul: Ah! The good old 'man-on-skateboard' false analogy!

We haven't had a false analogy for a while, & I already debunked this example once on this thread; but as you clearly have not read, or not understood, my post then I will repeat it...

Special for you, like!

So; according to NASA, the skateboard represents the rocket, the man represents the engine & the ball represents the rocket exhaust.

This is false.

In fact, it is the man's arm, in thrusting upon the ball, that represents the exhaust, whilst the ball represents an outside mass that the exhaust thrusts upon.

You see what they did there?

Thus, the man on the skateboard represents Object A, the ball represents Object B, & the requirements of Newton's 3rd law are fulfilled.

Rayzor; I don't care if you think I understand Newton's 3rd or not; your behaviour today has confirmed to any neutral reader that nothing you say is worthy of being taken seriously.

So it's your contention that if the man was sitting in a rocket in space and threw the ball  out the back that  the rocket wouldn't move?    Just a yes or no will suffice.

Rockets don't throw balls out the back, rayzor.

You haven't understood my post, have you?

Don't worry though; others will, no matter how hard you try to stop them.

Rockets don't throw balls out the back, rayzor.

You haven't understood my post, have you?

Don't worry though; others will, no matter how hard you try to stop them.

Why not?   Don't you agree that throwing balls out the back of a rocket would provide propulsion? 

Why not?   Don't you agree that throwing balls out the back of a rocket would provide propulsion?

He seems to be of the opinion that rocket exhaust is still part of the rocket. Somehow.

Don't you agree that a rocket does not have a man in the back of it throwing balls out?

We can do this as long as you like, ausGeoff...

& at the end of it I'll just re-post my unrefuted debunking of NASA's silly man-on-skateboard false analogy.

For the third time...

It's up to you.

B.j; I agree, it is a poor analogy for rocket propulsion in the first place.

But I have made it as correct as possible.

Logical minds will see this; whether that includes yourself too, I do not care.

B.j; I agree, it is a poor analogy for rocket propulsion in the first place.

But I have made it as correct as possible.

Logical minds will see this; whether that includes yourself too, I do not care.

If your analogy relies on something being forced out of a rocket to still be part of said rocket, it's long since left 'poor analogy' behind and is just wrong.

Yes, there are balls flying out the back. Ever heard of atoms?

Don't you agree that a rocket does not have a man in the back of it throwing balls out?

We can do this as long as you like, ausGeoff...

& at the end of it I'll just re-post my unrefuted debunking of NASA's silly man-on-skateboard false analogy.

For the third time...

It's up to you.

B.j; I agree, it is a poor analogy for rocket propulsion in the first place.

But I have made it as correct as possible.

Logical minds will see this; whether that includes yourself too, I do not care.

One thing you said there is correct,  we can do this for longer than you can,   I'm getting to like being mistaken for ausGeoff, maybe I should just play along. 

Quote from: Rayzor on June 20, 2015, 08:16:22 AM

Why not?   Don't you agree that throwing balls out the back of a rocket would provide propulsion?

He seems to be of the opinion that rocket exhaust is still part of the rocket. Somehow.

I'm struggling to get a clear statement of any kind out of him,  it's mostly incoherent gibberish,  and poorly constructed logic.   I think he is trying to say something about Newtons Third Law.  But god only knows what he wants to say.

Like I said, it's a poor analogy for rocket propulsion in the first place; it is more of an analogy for the recoil of a gun.

Still, I have corrected it as best I can, & logical minds will see the truth of what I say.

It is no surprise that you can not understand this, as you also do not understand that a rocket cannot be both Object A and Object B in a Newtonian action-reaction pairing.

But if you need to believe such impossible things in order to keep your space-fantasies alive, so be it.

Believe what you like; just don't get angry when I, or others, refuse to join you in your dream-world.

Misero: Here we go... you, too have missed my point completely; quel surprise!

You lot should take the following as your motto: False Analogies FTW!!!!!!!!!!!!!!!!!!!

& ausGeoff: what I said is perfectly clear; just shouting that it isn't does not make it true.

Words are not the same as Reality, no matter how desperately you wish they were.

It is no surprise that you can not understand this, as you also do not understand that a rocket cannot be both Object A and Object B in a Newtonian action-reaction pairing.

Here we go again,   just  take deep breaths and try to describe clearly what your point is...    Lets's start simple,   What is Object A and Object B  in your analogy?

I already told you.

Learn to read.

I suppose it's impossible to retype things for us poor unenlightened sheeples?

I'd prefer that you just learn to read.

& I never called any of you 'sheeple'; it is a silly & unhelpful term.

Sokarul: Ah! The good old 'man-on-skateboard' false analogy!

We haven't had a false analogy for a while, & I already debunked this example once on this thread; but as you clearly have not read, or not understood, my post then I will repeat it...

Special for you, like!

So; according to NASA, the skateboard represents the rocket, the man represents the engine & the ball represents the rocket exhaust.

This is false.

In fact, it is the man's arm, in thrusting upon the ball, that represents the exhaust, whilst the ball represents an outside mass that the exhaust thrusts upon.

You see what they did there?

Thus, the man on the skateboard represents Object A, the ball represents Object B, & the requirements of Newton's 3rd law are fulfilled.

Rayzor; I don't care if you think I understand Newton's 3rd or not; your behaviour today has confirmed to any neutral reader that nothing you say is worthy of being taken seriously.

In a rocket the gas it ejects could be considered an outside force and the rocket pushes on it because the gas is under pressure and trying to expand in all directions including forward.  The same thing applies because the same thing is happening.  Don't tell me you think conservation of momentum is true unless rockets are involved...

I don't think conservation of momentum has any relevance if your model of rocketry is clearly violating Newton's 3rd Law to start with.

Or do you think you can have one without the other?

Bear in mind what I said about Words not being the same as Reality before you answer.

I don't think conservation of momentum has any relevance if your model of rocketry is clearly violating Newton's 3rd Law to start with.

Or do you think you can have one without the other?

Bear in mind what I said about Words not being the same as Reality before you answer.

Conservation of momentum is actually derived from Newton's 3rd law, and as long as all the laws of motion are followed the center of mass of a closed system will never move under any circumstances.  If rockets work how you suggest then they would break conservation of momentum because the gas would move away from the center of mass while the rocket stayed put, this would mean  that the center of mass between the rocket and the gas would magically move despite conservation of momentum.

Rockets do not break Newton's 3rd law, in fact Newton's 3rd law is why people first believed that rockets work in a vacuum.  The action of ejecting gas has a reaction of moving the rocket, if that didn't happen then it would break Newton's 3rd law.

It is always easier to discuss with numbers, e.g.

Imagine a rocket with total mass m₀ 10 000 kg of which 5 000 kg is fuel. All fuel is ejected as gas (mass 5 000 kg) at v_e 2 500 m/s velocity (relative the rocket) from the nozzle at the aft end of the rocket. Rocket mass becomes m₁ 5 000 kg, while the rocket attains speed (delta-v) 1 733 m/s according Tsiolkovsky*.

Assume that this takes 100 seconds.

The space ship then travels 86 643 m in one direction leaving a big cloud of exhaust gas extending 336 643 m behind with variable speeds.

Before start the momentum of the rocket with fuel is 0. After accelerating the rocket the momentum of the empty rocket is 8,665 Mkgm and the momentum of the exhaust gas is -8,665 Mkgm. The total momentum remains 0.

Imagine the same rocket having speed 1 733 m/s (it has been given this speed by another rocket). It has a momentum of 17.33 Mkgm. The rocket  is now braking for 100 seconds burning 5 000 kg of fuel.

The exhaust is now ejected from the nozzle in the direction of braking and after 100 seconds the speed (delta v) is 0.

The exhaust gas cloud extends 336 643 m as before, but the space ship has travelled 86 643 m into this exhaust cloud.  The total momentum of rocket and exhaust remains 17.33 Mkgm.

Any space ship will sooner or later run out of fuel unless you find a way to fill up in space.

*Konstantin E. Tsiolkovsky has established that the change in velocity, Delta-v, of a spacecraft in vacuum space (no influence of gravity of an adjacent planet or Moon) is a function of the mass ratio (spacecraft mass before, m₀ and after, m₁ firing the rocket engine, difference m₀ - m₁ being the fuel mass ejected as exhaust gas and the exhaust velocity v_e of gas leaving the space ship rocket nozzle.
Delta-v = v_e ln (m₀/m₁)
Example - you want to change speed of the 10 000 kg (m₀) space ship. You have 5 000 kg of fuel aboard and it is ejected at a velocity v_e 2 500 m/s.  m₁ = 5 000 kg. Delta-v = 1 733 m/s.

Sokarul: Ah! The good old 'man-on-skateboard' false analogy!

We haven't had a false analogy for a while, & I already debunked this example once on this thread; but as you clearly have not read, or not understood, my post then I will repeat it...

Special for you, like!

So; according to NASA, the skateboard represents the rocket, the man represents the engine & the ball represents the rocket exhaust.

This is false.

In fact, it is the man's arm, in thrusting upon the ball, that represents the exhaust, whilst the ball represents an outside mass that the exhaust thrusts upon.

You see what they did there?

Thus, the man on the skateboard represents Object A, the ball represents Object B, & the requirements of Newton's 3rd law are fulfilled.

Incorrect. The ball is equal to the exhaust gas. How can the ball move the man if it's 5 feet away? This is just like a bullet in a gun. If the ball was the outside mass, then the mass of the ball wouldn't matter. You think he will move if he throws a balloon? No, he won't. This shows that the man moves because he throws a mass. Just like rockets. 

The truth is right there in front of you, just open your eyes.

LOL!!!

You really don't want to understand what I say, do you?

OF COURSE the movement of the man depends on the size of the mass he throws - because he has to PUSH ON IT HARDER!!!

Thus, the strength of his arms equates to the strength (i.e. velocity) of the exhaust.

THRUST, you know; look up the dictionary definition.

The truth is right there in front of YOU too, sokarul; just keep your eyes CLOSED...

Just LOL!!!

LOL!!!

You really don't want to understand what I say, do you?

OF COURSE the movement of the man depends on the size of the mass he throws - because he has to PUSH ON IT HARDER!!!

Thus, the strength of his arms equates to the strength (i.e. velocity) of the exhaust.

THRUST, you know; look up the dictionary definition.

The truth is right there in front of YOU too, sokarul; just keep your eyes CLOSED...

Just LOL!!!

This goes against everything you say, thanks for finally seeing rockets work as claimed.

No it doesn't.

I know you really want it to.

But it doesn't.

The man's arm, in THRUSTING UPON  the OUTSIDE MASS of the ball, represents the rocket exhaust.

So the harder his arm (the exhaust) thrusts upon the outside mass, the further he will travel.

Simple, eh? Newton's 3rd is...

But not for you, inexplicably.

Nice try, though, but Words are not the same as Reality, sadly for you & your space-dreams...

P.s. Heiwa: no, it is not 'easier to discuss with numbers'; especially yours & rayzors!

Just show me some evidence for your model, please....

Oh, wait - you can't!

LOL!!!

No it doesn't.

I know you really want it to.

But it doesn't.

Yes it does.

The man's arm, in THRUSTING UPON  the OUTSIDE MASS of the ball, represents the rocket exhaust.[/quote]
He is accelerating the ball. He is applying a force to it. In return, the ball also accelerates him. Since the ball has much less mass, he accelerates less.

So the harder his arm (the exhaust) thrusts upon the outside mass, the further he will travel.

This is indeed true. Since a simplified equation is mv=-mv. If the ball leaves with move vidoecity, he will have more velocity.

Simple, eh? Newton's 3rd is...

But not for you, inexplicably.

No, it is.
But not for you. The ball starts as a part of him and then is ejected. Just like rocket fuel.

Denpressure adequately explains the Newton carry on with medicine balls and such with people on skates; skateboards or whatever.
Whatever dense object a person is holding, it will have more force against atmospheric resistance due to it resisting that pressure against it's dense mass.
That's why a beach ball doesn't stack up against it, because a beach ball is made up mostly of atmospheric equalized pressure, so all you're throwing is the plastic skin as any dense mass....plus the air fill inside which is minimal against your own dense mass.

Make sense?

Let's make it a bit easier for people to understand. You can do this for pennies.

Get 3 pieces of wood. Some mdf or plyboard or chipboard, etc. about 3 feet by 3 feet should suffice.

Screw two boards together so you now have one board twice as thick as the other board left.
Now cut large holes into the thicker board, so it looks something like a large connect 4 board, until both boards are the same weight.

Ok, now get another person to hold one of the boards while you hold the other. Now race each other over a short distance and see who wins the race.
You'll find that the person with the holed up double board will win easily because he's running into much less resistant force due to his holed board allowing air flow through it.


Now get on a skate board and throw both boards and see how far the skateboard moves backwards. You'll find that the board with no holes, creates a larger resistance on your body when you throw it forward because it's full size has to push all that air away, compressing it, which springs back onto the persons hands.
The holed board will have much less resistance to it because most of the air can compress through the board and be dissipated around the person.

The sooner people get to grips with denpressure, the sooner a lot of things will become clear about a lot of stuff. Gravity and silly space rocketry will be understood for what they are....a con.

Denpressure adequately explains the Newton carry on with medicine balls and such with people on skates; skateboards or whatever.
Whatever dense object a person is holding, it will have more force against atmospheric resistance due to it resisting that pressure against it's dense mass.
That's why a beach ball doesn't stack up against it, because a beach ball is made up mostly of atmospheric equalized pressure, so all you're throwing is the plastic skin as any dense mass....plus the air fill inside which is minimal against your own dense mass.

Make sense?

Let's make it a bit easier for people to understand. You can do this for pennies.

Get 3 pieces of wood. Some mdf or plyboard or chipboard, etc. about 3 feet by 3 feet should suffice.

Screw two boards together so you now have one board twice as thick as the other board left.
Now cut large holes into the thicker board, so it looks something like a large connect 4 board, until both boards are the same weight.

Ok, now get another person to hold one of the boards while you hold the other. Now race each other over a short distance and see who wins the race.
You'll find that the person with the holed up double board will win easily because he's running into much less resistant force due to his holed board allowing air flow through it.


Now get on a skate board and throw both boards and see how far the skateboard moves backwards. You'll find that the board with no holes, creates a larger resistance on your body when you throw it forward because it's full size has to push all that air away, compressing it, which springs back onto the persons hands.
The holed board will have much less resistance to it because most of the air can compress through the board and be dissipated around the person.

The sooner people get to grips with denpressure, the sooner a lot of things will become clear about a lot of stuff. Gravity and silly space rocketry will be understood for what they are....a con.

Have you actually done EITHER of these experiments yourself.