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Messages - Cuddyer05

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Because they believe its pushing off the air.

That is why I am asking about conservation of momentum.  By applying this general principle of physics, we can show that the rocket can indeed move forward without the need of an external pushing force (air pushing the rocket).

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I guess I am still confused as to why someone could not simply apply conservation of momentum to show that rockets can fly in a vacuum since my previous question has not been answered.  There is a lot of talk about air pressure and expansion of gases that is really not necessary to answer the primary question.  I think we all agree that when a rocket is launched, gas is pushed out of the back of the rocket.  Since a rocket starts at rest, the initial momentum of the rocket, its fuel, and the gas that will eventually be formed is zero.  As gas gets pushed out the back of the rocket, the rocket and the remaining fuel MUST move forward to conserve momentum.

p0=pf

0 = mgasvgas+mrocketvrocket

-mgasvgas/mrocket = vrocket

Seems pretty straight forward that a rocket would move in the opposite direction of the gases being expelled from the back of rocket.

3
I guess I am still confused as to why someone could not simply apply conservation of momentum to show that rockets can fly in a vacuum since my previous question has not been answered.  There is a lot of talk about air pressure and expansion of gases that is really not necessary to answer the primary question.  I think we all agree that when a rocket is launched, gas is pushed out of the back of the rocket.  Since a rocket starts at rest, the initial momentum of the rocket, its fuel, and the gas that will eventually be formed is zero.  As gas gets pushed out the back of the rocket, the rocket and the remaining fuel must move forward to conserve momentum.

p0=pf

0 = mgasvgas+mrocketvrocket

-mgasvgas/mrocket = vrocket

Seems pretty straight forward that a rocket would move in the opposite direction of the gases being expelled from the back of rocket. 

4

Lacki and scepti both dont believe in "conventional" physics.
Which is the issue here.
They believe rockets and med balls are pushing off the stationary air.

You can "not believe" all you want.  I would like to see a mathematically consistent and logical way to deal with every situation where conservation of momentum applies that does not use conservation of momentum. 

5
The answer to "can rockets fly in a vacuum?" is a pretty simple one.  Yes, they can.  Apply the law of conservation of momentum to rocket and the gases it will exhaust.  You will see fairly quickly that as mass moves out the back of the rocket, the rocket itself must move in a forward direction. 

The statement "combustion can't happen in space" really depends on your definition of combustion.  If you are defining combustion as a reaction which requires oxygen from the environment as a reactant, this statement would be correct.  Would you consider the termite reaction to be combustion?  It does not require oxygen from the environment since the substances being used are self-oxidzing.  It would probably be more accurate to think of the reaction in a rocket engine as a redox reaction since the fuels being used self-oxidize without needing an external oxygen source.

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Flat Earth Q&A / Re: Maths in regard to the theory
« on: November 03, 2019, 06:18:35 PM »
As a physicist, I would agree with your statement.  There are certainly mathematical ideas which are logically consistent with mathematics and may be very elegant solutions yet have no bearing on what the real physical world looks like or behaves like.

As a keen mathematician, I revel in the chance to prove things in terms of equations. I am wondering if there are any ones that work for the flat earth but not the globe earth

Mathematics is not physics. That means, for example, that in mathematics you can have and calculate with n dimensions. But that does not mean, that reality has n dimensions. Physics needs empirical data, mathematics does not.
To me mathematics is the poetry of god, showing the absolute beauty of creation.
So, it is not a mathematical thing, if flat earth exists or not.

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Flat Earth Q&A / Re: A couple of questions
« on: November 03, 2019, 06:10:47 PM »
John, I think there is a flaw in your use of statistics.  Let's assume that the odds of Earth (or any planet) being flat are non-zero, since I would argue whether or not a planet is round or flat should be an independent event, seeing more round planets does not change the likelihood that Earth is flat.

Let's use your goose example.  Assume that we know there is a one out of every one thousand chance that a goose is white and not gray.  I have captured a goose and put it in a sealed cardboard box.  You are asked to predict if the goose in the box is white or gray without looking in the box.  Would seeing nine hundred and ninety-nine gray geese outside your window change your prediction of whether the goose is white or gray?

Only Flat Planet

This is an interesting question.

Asking why is earth the only flat planet betrays a logical fallacy. Karl Popper talks about this in Logic of Scientific Discovery, and its a well covered topic in philosophy of science, presenting one of the largest issues with empiricism.

As it turns out, each planet we view that is round actually makes it more probable that the earth is flat - this is one of the issues behind the problem of induction. Since the earth being flat has a non-zero probability, each time we observe a round object it reduces the solution space, thus making the non-zero probability have a higher likelihood.

More than this, the idea is logically faulty. I may see a grey goose out my window each day. Does this mean all geese are grey?  In other words, since I can say Object A and Object B are both blue, does that make Object C blue? or Object D? Or all other objects?!


It is possible there are other flat planets, and even NASA has purportedly observed many flat bodies.


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