evidence of moon missions

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Re: evidence of moon missions
« Reply #90 on: January 23, 2013, 08:25:00 AM »
Thanks for answering my questions, I have another though.

I've heard this experiment described to you so I know you're familiar with it.

If you sit on a chair with good wheels and on a low friction surface and start throwing medicine balls out in front of you then you will start rolling backwards. Can you explain what is happening?

The way you've described stuff above you're pushing against the ball as you throw it and the ball in turn is pushing against the air but I'm curious why if that's the case the ball doesn't just fall to the ground when you stop pushing.
I understand the action and reaction of a person on a chair with a medicine ball or on ice skates on a skating rink and this guise is used to make out that rockets use the same thing, which is rubbish to be honest.

Rockets do not throw medicine balls, or cannon balls or super dense massive lead balls from it's rear constantly, it ignites and then simply " burns" fuel.

This is the con job that people get hit with because it appears to be correct, yet it's two totally different means of propulsion.
A constant set of explosions like they say it is would blow the  rocket to pieces.
I don't expect you to believe it as you have your own mind, yet have a serious think about how it's easy to be duped either way, because, even I agree it is a clever mind busting job they have done to convince even the smartest people.

While a rocket may not be throwing balls out of the back a water rocket is (well tiny molecule sized watery ones :))
It's not the water that's acting against the air, it is the actual air acting against air, as in the air, "under pressure" racing past the water or through it and expelling it as a consequence, that's all.

So why have water in the rocket at all, surely it would work better with just air
To add mass to the bottle so it will push through the air above it and not simply go into a spin if compressed air alone was used.

Might I suggest building a water rocket or two and giving both scenarios a try, but instead of letting them fly in the air strap both rockets to a toy car or something like it so that the rocket can't spin off. Pump both the rocket with water and without up to the same pressure and see what happens when you let them go.

I predict the water rocket will go further! Prove me wrong

edit: You have to stand them up so the exhaust from the bottle is at the bottom (otherwise the water doesn't get pushed out) then use a bit of tube or something to direct the expelled gas etc in the right direction
« Last Edit: January 23, 2013, 08:30:41 AM by Manarq »
I'd like to agree with you but then we'd both be wrong!

Re: evidence of moon missions
« Reply #91 on: January 23, 2013, 08:51:14 AM »
The efficiency has nothing to do with the rate at which the exhaust is released.
Why use evidence
Ok

Re: evidence of moon missions
« Reply #92 on: January 23, 2013, 08:54:51 AM »
The exhaust doesn't need to push off of anything. If you think about it, the exhaust is no longer in contact with the rocketship. This means that if it pushes off of anything it will only affect itself and what it pushes off of. So really what happens to the exhaust after it leaves the rocket doesn't do anything to the rocket.
So why have a burning rocket in the first place? Why not just fill it with compressed air and some water?

Yes I know that sounds silly but if you think the burning of fuel isn't the reason a rocket works, then why the hell burn fuel.

Think about it.

That's not too efficient to have air and water since fuel has more potential energy. They burn fuel to expell the exhaust through the bottom of the rocket.
Why use evidence
Ok

Re: evidence of moon missions
« Reply #93 on: January 23, 2013, 09:05:13 AM »
The efficiency has nothing to do with the rate at which the exhaust is released.
Ok then, the rocket is expelling both water and air from a simple straight threaded opening.
Explain to me where the force is acting on that bottle would be pushing it upwards.

I don't quite understand the question. Do you mean in the rocket engine itself?

As for your post above he will need to know the masses of you, the friend, and the force exhibited.
Why use evidence
Ok

Re: evidence of moon missions
« Reply #94 on: January 23, 2013, 09:06:57 AM »
The exhaust doesn't need to push off of anything. If you think about it, the exhaust is no longer in contact with the rocketship. This means that if it pushes off of anything it will only affect itself and what it pushes off of. So really what happens to the exhaust after it leaves the rocket doesn't do anything to the rocket.
So why have a burning rocket in the first place? Why not just fill it with compressed air and some water?

Yes I know that sounds silly but if you think the burning of fuel isn't the reason a rocket works, then why the hell burn fuel.

Think about it.

That's not too efficient to have air and water since fuel has more potential energy. They burn fuel to expell the exhaust through the bottom of the rocket.
And how does the fuel get expelled through the bottom of the rocket?
What force is used to expel it?

The fuel isn't expelled, the hot gas created as a result of burning the fuel is expelled from the bottom. The hot gas is expelled for the same reason that the internal combustion engine works ie the hot gas takes up more space than the solid/liquid fuel and creates pressure.
I'd like to agree with you but then we'd both be wrong!

Re: evidence of moon missions
« Reply #95 on: January 23, 2013, 09:12:09 AM »
The exhaust doesn't need to push off of anything. If you think about it, the exhaust is no longer in contact with the rocketship. This means that if it pushes off of anything it will only affect itself and what it pushes off of. So really what happens to the exhaust after it leaves the rocket doesn't do anything to the rocket.
So why have a burning rocket in the first place? Why not just fill it with compressed air and some water?

Yes I know that sounds silly but if you think the burning of fuel isn't the reason a rocket works, then why the hell burn fuel.

Think about it.

That's not too efficient to have air and water since fuel has more potential energy. They burn fuel to expell the exhaust through the bottom of the rocket.
And how does the fuel get expelled through the bottom of the rocket?
What force is used to expel it?

It is forced out of the bottom through what I believe is a chemical reaction from when the engine is lit.
Why use evidence
Ok

Re: evidence of moon missions
« Reply #96 on: January 23, 2013, 09:16:48 AM »
The efficiency has nothing to do with the rate at which the exhaust is released.
Ok then, the rocket is expelling both water and air from a simple straight threaded opening.
Explain to me where the force is acting on that bottle would be pushing it upwards.

I don't quite understand the question. Do you mean in the rocket engine itself?

As for your post above he will need to know the masses of you, the friend, and the force exhibited.
I want you to tell me, in what I've described, what force is acting against the bottle/rocket to push it upwards.

Also, the friend is of equal size and mass.

Oh it is pushing out the exhaust and through Newtan's third law it pushes back on it.

Being equal mass is not sufficient info, you'd need specific masses and force applied, no?
Why use evidence
Ok

Re: evidence of moon missions
« Reply #97 on: January 23, 2013, 09:28:38 AM »
The exhaust doesn't need to push off of anything. If you think about it, the exhaust is no longer in contact with the rocketship. This means that if it pushes off of anything it will only affect itself and what it pushes off of. So really what happens to the exhaust after it leaves the rocket doesn't do anything to the rocket.
So why have a burning rocket in the first place? Why not just fill it with compressed air and some water?

Yes I know that sounds silly but if you think the burning of fuel isn't the reason a rocket works, then why the hell burn fuel.

Think about it.

That's not too efficient to have air and water since fuel has more potential energy. They burn fuel to expell the exhaust through the bottom of the rocket.
And how does the fuel get expelled through the bottom of the rocket?
What force is used to expel it?

The fuel isn't expelled, the hot gas created as a result of burning the fuel is expelled from the bottom. The hot gas is expelled for the same reason that the internal combustion engine works ie the hot gas takes up more space than the solid/liquid fuel and creates pressure.
But the hot gas is expelled outside of the rocket, as a burn.

Ok , have a think on this. Why do they have different types of nozzles on the bottom of rockets, as in diameter?
What purpose do they serve in terms of wide or thinner ones.

The burn happens inside the rocket and 'shoots' out of the bottom.

To my knowledge, larger nozzles provide more thrust and are less efficient, so smaller ones are more efficient and provide less thrust.

A while back you said something about the water rockets and efficiency and I said you were wrong but looking back you may not have been, so I apologize.
Why use evidence
Ok

Re: evidence of moon missions
« Reply #98 on: January 23, 2013, 09:32:20 AM »
I think I see what your problem is with this. You can't see how the energy of the material being pushed out of the rocket is translated into forward momentum for the rocket, ie if you want to jump up you have to press against the ground and accelerate your body up whereas a rocket in your opinion isn't pushing against anything.

I'd like to agree with you but then we'd both be wrong!

?

MrT

  • 211
Re: evidence of moon missions
« Reply #99 on: January 23, 2013, 09:34:40 AM »
I don't need you to do the math. All I want you to do is have a wild guess as to what would happen to the person suspended in terms of upward movement. We know what happens to the guy who's thrown; he just goes splat.  ;D

But the math is very important.  A wild guess will not get you very far when dealing with physics.  An educated guess could be made without complete math if some of the variables were known, but a wild guess based on no known variables is meaningless.

You seem to make (and demand from others) conclusions about whether or not something would or would not work based on wild guesses.  Any conclusions based on actual study, math and testing you conclude are false due to being based on "what you are told".

I can't imagine you aren't simply having a bit of fun.  That's fine, because I don't suppose anybody would be here if they didn't get some kind of satisfaction out of the discussion, whatever it is. 
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand

Re: evidence of moon missions
« Reply #100 on: January 23, 2013, 09:49:20 AM »
Quote
How can out rushing water and air push back on the bottle rocket? Can you describe a little bit in a bit of detail how this happens?

I'm not to good at describing these things really :p Ill try to think of a way though.

Quote
I don't need you to do the math. All I want you to do is have a wild guess as to what would happen to the person suspended in terms of upward movement. We know what happens to the guy who's thrown; he just goes splat.  ;D

Well, the person wouldn't move much, since it would be kind of hard to throw someone down who is already under you.
Why use evidence
Ok

?

MrT

  • 211
Re: evidence of moon missions
« Reply #101 on: January 23, 2013, 11:05:08 AM »
I understand that the rocket on Earth uses fuel, ejected with a massive amount of force against the atmosphere, which tries to force it's way past the colder denser air below it, making the air expand.

This probably might not be the right explanation, yet I liken it to two men on a train track using a see saw level to propel the buggy, one pushing up and the other pushing down and imagining them going vertical.

Like I said, my explanation isn't the best but I think you get my meaning.

The rocket does eject hot exhaust with massive force.  But the thrust generated isn't due to the exhaust being ejected "against the atmosphere".  The massive force of the exhaust ejection itself creates an equal force in the opposite direction, creating thrust.

With the water rocket, the water is not simply slowing the release of the air.  The air does not push past the water and create the thrust, with the water having no effect.  The water is ejected before the air, and the water being ejected creates the thrust.  I had a water rocket (many, many years ago).  I tried different nozzle sizes and different volumes of water vs. air.  You should try it some time.  Try some things for yourself and see some things in action.

Have you seen fire hoses where it takes multiple fireman to hold the hose in place because the thrust created by the water flow would be too great for one person to handle?  In this case there is no compressed air to cause thrust, just water flow created by a pump.  The force of the water being ejected from the hose nozzle creates the thrust.
« Last Edit: January 23, 2013, 11:10:30 AM by MrT »
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand

?

MrT

  • 211
Re: evidence of moon missions
« Reply #102 on: January 23, 2013, 11:34:23 AM »
Rockets will not work in space. As soon as the fuel was thrust out of the rocket, the vacuum would immediately swallow it up as fast as it came out.

Also, when you put air into your water bottle, does it push past the water and sit on top of it?

You have no proof other than "because that's what I think" to say that rockets won't work in space.  The vacuum of space won't "swallow" the fuel.  The intense pressure created by the burning fuel will be ejected into space, where it will quickly de-compress.  However, the force with which it is ejected will create an equal force in the opposite direction, resulting in thrust for the rocket.

Yes, air is less dense than water, so the air rises to the top of the bottle as the bottle is pressurized.  However, since all the contents of the bottle are under the same pressure (water and air) the water remains more dense than the air, and the air stays above the water.  When the valve is opened, the air cannot force its way past the water, due to the water's greater density.  This means that the water is ejected first, and if any pressure remains after all the water is gone, the remaining pressurized air will also vent from the bottle.  Unless the rocket turns upside-down or is severely agitated, the air will remain above the water and the water will come out first.  The water will not force it's way back down through the water and come out first. 

If I have a container full of liquid I can pump pressurized air into the top of the container to force the liquid out the bottom.  The air will not force it's way past the liquid and come out first. 
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand

?

MrT

  • 211
Re: evidence of moon missions
« Reply #103 on: January 23, 2013, 11:48:54 AM »
We have all farted in the bath right?

What happens.

Speak for yourself.

How is that relevant?

Like I said, having a bit of fun.
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand

Re: evidence of moon missions
« Reply #104 on: January 23, 2013, 12:28:00 PM »
Rockets will not work in space. As soon as the fuel was thrust out of the rocket, the vacuum would immediately swallow it up as fast as it came out.
Actually they will, and it's already been explained in a 50 page thread.

Is your refusal to accept how they work based on what appears to be a bias against science in general due to a deep seated emotional resentment towards society for lying to you about the Easter Bunny and Santa Claus, and possibly some other fairy tales, and the hurt and sadness you felt when you found out they weren't real?

Afterall, would someone who is 'questioning' instead of 'biased', use terms like "astro-liars" in place of 'astronauts'?

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MrT

  • 211
Re: evidence of moon missions
« Reply #105 on: January 23, 2013, 02:24:02 PM »
It's relevant because it shows that air forces it's way through water.

The air will "float" up because it is less dense than water.  This does not in any way prove or in any way support that the pressurized air in the toy rocket will move down below the water and exit the nozzle first.

If what you are saying was true then spray cans, pump-up water sprayers for weed killer, turkey basters, toy water rockets, etc. etc. (and a million other examples) would not work.

But what you are saying is not how it works.  The pressurized air won't force it's way past the water, it will simply force the water down and out and the pressurized air will vent after the water is gone if there is any pressure left. 

And what about my fire hose example?  There is no pressurized air in that situation, just a high volume flow of water, which creates enough thrust that it takes multiple people to hold the hose.
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand

?

MrT

  • 211
Re: evidence of moon missions
« Reply #106 on: January 24, 2013, 04:17:13 AM »
No offense but I think you need to learn a little bit of basic physics and physical sciences (unless you are just playing) before a discussion like this can continue or ever hope to get anywere.

I will only point out that in a pressurized container (the bottle in our example) the water and the air will be under the same pressure.  It's not as if the high pressure air is pushing out past the low pressure water.  The water doesn't compress, but it is under the same pressure as the air. 

I think a good example of a device which works totally on the basis that the air will not force its way down past the liquid is a liquid manometer.  This device is a very simple and accurate measurement tool.  It would not work if what you say is true.

« Last Edit: January 24, 2013, 04:35:13 AM by MrT »
The above is not meant to be an attack or inflammatory, it's just what I think.

Quote from: Tom Bishop
I don't understand