I recently came across the video on YouTube
by a flat-earther who was claiming that rockets
don't work in space.
In this video I'm going to go ahead and review
the other video and point out the things that
they got right as well as point out the things
that they got wrong.
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or hoping to become aerospace engineers, go
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to the next level.
Let's go ahead and start reviewing that video.
"well basically it's just impossible it cannot
work in the vacuum of space physically it's
impossible" This is what we call an unqualified
assertion.
"so what about all the scientists are they
all lying" Lying? Really?
"The thing is we have understood the word
scientist wrong look i'm a scientist i'm a
mechanical engineer and i have a masters degree
in technical physics and i work as a research
and development scientist" I would caution
you on how you try to establish your credibility.
You're just stating assertions and then stating
your qualifications but we haven't yet heard
any explanations, experiments, theories, formulas,
mathematical models.
So it's just coming off as an appeal to authority
right now.
"but when you say a scientist you think these
guys are out there and they are just exploring
the universe and trying to find the secrets
of the universe no its not like that they
pay us to do certain things certain tasks
and if they dont pay me i'm not going to go
search those" Um, problem here.
A scientist is by definition someone who studies,
or has an expert knowledge on the natural
or physical sciences.
That is the Oxford definition of a scientist.
And what is science except for applying experimentation
and mathematical modeling to understand the
world around us, to learn these secrets about
how it operates, how it functions.
What you're describing sounds more like engineering.
Every once in a while in our coursework, we
hear that the difference between a scientist
and an engineer is that a scientist studies
the world around him while an engineer makes
the world around him.
The idea is that the scientist is just in
it to study and understand while the engineer
learns these scientific principles and applies
it to making a machine or structure or some device.
So it sounds like you might be confusing a
little bit science and engineering right here.
Now just because you are in it for the money
doesn't mean we all are.
Taking this at a higher level, what are we
doing having a discussion on finances?
Let's leave that to a budget meeting.
This is supposed to be a scientific argument
to back your claim that rockets don't work in space.
I'm still waiting to hear why.
"even if there are some people like me who
do think about it the thing is that since
child hood they tell us that rockets do work
and that nasa is sending stuff up into the
space and so youre just programmed since childhood
youre not going to be questioning that program
and even if you do question that program people
will laugh at you people will judge you they
will think you are stupid so you end up losing
your job and friends and stuff so the scientists
they don't do that to themselves it just a
stupid thing to do even if its the truth but
you just don't do it" Alright, I can't take
it anymore.
Let's have a discussion on the method for
doing science and the method for making me
scientific argument, A.K.A., let's talk about
the scientific method.
Time to hit the chalkboard.
The scientific method is usually broken down
into a couple of steps.
Depending on whether it's broken down into
four steps or five steps or six steps, it
doesn't really matter.
It always follows the same pattern.
The scientific method usually starts with
an observation.
You notice some phenomena in the world and
you don't understand what's happening.
As you observe these physical phenomena in
the world, it leads you to question how its
operating, or what's the driving force or
principle behind the phenomena.
And so that leads you to your question.
To try and answer the question you have to
come up with hypotheses on what potentially
could be causing this event to occur, what
could be causing it to not occur, and so that's
what you're doing when you are hypothesized.
You're trying to rationalize in your head
what's going on.
So once you hypothesize in your head what
could be occurring, you develop an experiment
to test that hypotheses.
You're trying to determine is my thinking
correct?
Is my hypotheses valid?
Is it invalid?
And, of course, there are certain qualifications
for your experiment.
It's supposed to be repeatable, it has to
be able to be proven wrong.
The idea is that you're trying to, with some sort of test, determine whether your hypotheses is valid or not.
So after you perform your experiment, you
look at your data.
Did it prove or disprove your hypotheses?
You might look at it to say is this actually
proving what I want it to prove? and this
is usually summed up or rationalized out in
the conclusion when you go over the results
from your experiment.
After that would be a peer-review step where
you just get other people in your field to
look over your hypotheses, and experiment,
and your analysis of the the data from the
experiment, and just go over your conclusions
to make sure that it seems valid.
Now my graphic here has it in a circle because
once you come up with conclusions that might
make you observe other phenomenon and then
you can start questioning what's going on there.
And it just starts the cycle over again.
Now if you notice, and most people don't,
in school when you're doing a lab and have
to write up the lab report, or if you're doing
a research paper, the different sections of
that paper will actually follow the scientific
method.
Now if you're also trying to "prove" or "disprove"
(and I put those in quotations of course)
if you're trying to provide evidence for or
a case for or against something you normally
want to follow the same method.
If you're just stating unqualified assertions
of "it just doesn't work" That's not how science
is done or argued.
It really just comes off as weak and that
you don't know what you're talking about.
You need to be able to explain the physical
phenomena of which you're arguing about.
You need to understand any experimentation
already done on the subject or have performed
experimentation yourself.
Then go over the results of that, talking
about, from a scientific point of view, the
scientific principles behind it.
You can't just say "my results are valid"
"my results are invalid".
You need to say why they're valid.
Show your work.
Show your math type of a thing.
And then in your conclusion is where you can
assert things based on the experimentation
and observations from before and send it out
for peer review.
This video is actually making the claim that in science were brainwashed to not question the program.
We just accept what they tell us and that's
how it works.
We just memorize and learn all this stuff
and regurgitate it.
We're not actually taught to question it ourselves
or think differently.
But, as you look here at the actual scientific
method, questioning is built into the method.
In fact, questioning is the very backbone
of the scientific method.
If we observe something we can't explain or
doesn't make sense, the scientific method
is designed to go and figure out what's going on.
The scientific method is what's used because
you ARE questioning the world around you.
For instance, if I let go of a balloon filled
with helium and it rises instead of falling
that will lead me to question my understanding
of gravity.
At which point, I would hypothesize why the
balloon rose instead of fell to earth like
my current understanding of gravity tells
me.
And so I would come up with some experiments.
What's going on chemically, or thermally,
or mechanically, to try understand why the
balloon rose instead of fell, all because
I found something that does not agree with
what I know.
Now to take it one step further: papers, being
published, trying to get the Nobel Prize,
or inventing something, or getting your name
in future textbooks, these are all highly
sought-after things.
And these are obtained by questioning the
current understanding of science.
So to say that science teaches us to not question
the program or to not question things is really
the exact opposite of what's going on.
Now about the whole "judging you, thinking
you're stupid, losing your friends and family"
that doesn't really happen in science.
That happens more when you follow crazy conspiracy
theories and try and back it up with pseudoscience.
Its just not really a thing.
"the reason that you do think that rockets
do work in the vacuum of space is because
of the third law of motion the third law of
motion states it says that for every action
there is an equal and opposite reaction" Yay!
Now I'm celebrating for two reasons.
The first is that we're actually starting
to talk about the science.
The second reason is that he correctly identified
Newton's third law of motion as the driving
principle behind rocket motion.
Let's see if he understands it.
"so its really easy to test that lets put
this into action an action is for example
i'm going to start punching now so i'm punching"
Alright, let's be very clear about our definitions here.
An action, or it's cousin the reaction, used
in the laws of motion is a very specific thing.
And that specific thing is a force: a push
or a pull.
So your first use of the word action as in
"let's put this to action" means more of "let's
try an experiment" or "let's test this out".
It's not the same use of the word action as
it's found in the laws of motion.
Now for your second use of the word action
you said something along the lines of "an
action is for example I'm going to start punching".
Now if we're talking about Newton's laws here,
for your example the action is not the punching.
The action would be the force at the punch
applies to something, that's the action, "so
im punching and i dont feel any reactions
do you see a reation i don't feel any reaction
but then i start punching the wall and i feel
the reaction you can try it you feel the reaction
it starts hurting and if i punch harder its
going to bleed and if i punch even harder
its going to break my bones".
Just because you don't see a reaction or feel
a reaction doesn't mean that there isn't a
reaction taking place.
Think of a mosquito.
You often don't feel a mosquito on your skin
until it bites you.
That's when you do that "AHH" .
Now, since you don't feel the mosquito as
it's on your skin, does that mean it's not
applying a force onto your skin?
We know that it's applying a force (since
it has landed on your skin) we just can't
feel the force because it's so small.
It is curious though that you recognize if
you punch the wall harder you'll have a different effect.
I wonder why you didn't apply that reasoning
to why you didn't feel anything while punching air.
"so it seems like the third law of motion
in order for you to get the reaction the equal
and opposite reaction you have to apply your
action on something if its nothing then you
don't get the reaction" Correct.
The third law describes the interaction of
forces between objects.
Specifically if I push on an object, the object
then pushes upon me.
That's the definition of the third law.
"for example if I'm now pushing myself I'm
pushing my hand and no reaction I don't feel
any push back but then i push the wall and
i fell the push back so you cannot just push
nothingness and expect something to happen
there has to be something".
 Run away!!!
All right, so let's look at what we know.
So what we know is that air has mass.
It's an object.
So if you apply a force on an object according
to the third law it's gonna push back on you.
Okay, okay.
So we know that.
Now, now this guy he says that when he pushes
he doesn't feel a reaction.
Do you know what that means?
Now since he can't feel anything on his hand,
that must mean he's not in air.
He must be filming in a vacuum chamber.
He must be a lizard person because only lizard
people don't need oxygen to survive.
We have an actual lizard person here.
He's not pushing on air.
He must be pushing on a vacuum because he
doesn't feel anything cuz we know air has mass.
So it must be in a vacuum.
He's a lizard person.
I guess maybe there's another option that
he's not applying the force on the air that
he thinks he is.
Or maybe that the force is too small he can't
feel it.
But that would mean he doesn't exactly understand
what gases are doing and I thought he had
a degree in physics.
Which one do you think is more likely?
If you think he could be a lizard person,
let me know in the comments below.
"i'm now pushing myself i'm pushing my hand
and no reaction i don't feel any push back
but then i push the wall and i feel the push
back so you can not just push nothingness
and expect something to happen there has to
be something".
You assume that if you're punching the wall
with the same "oomph" that you're punching
the air that you're applying the same force
onto the wall as you are onto the air right.
You feel that same "oomph" in your muscles
so obviously "you're applying the same force".
The problem is that's not the case.
You're not applying the same force on a solid
wall as you are on the air.
And this is why you don't feel a reaction
force when you punch the air.
Your sensor, your tactile sense or in your
hand, your skin, just isn't able to pick it up.
Unfortunately, at this time you can't just
go buy more expensive sensor.
Maybe in the future.
Also keep this part of the video in mind later
when he starts talking about how a rocket
is able to ascend it in a space by pushing
on air.
Let's go ahead and talk about normal forces
in a solid then we'll compare that to normal
forces in a gas.
Before we talk about forces on a solid, let's
talk about what a solid is.
A solid is something that holds both its shape
and its volume.
A solid does this because the different particles
that make up the solid they don't want to
move past each other.
They're held in their place by these bonds
between the different particles, the inter-molecular bonds.
This is different from a liquid where they
want to slide past each other or in a gas
when they're free to move about and they just
bounce around and every once in a while collide
with each other.
What this means is that if you try to push
one solid into another solid it's going to
resist that.
They don't want to occupy the same space at
the same time.
This is because those particles have a strong
bond between each other where it doesn't want
to allow its particles to move past each other.
So if you take your fist, and you push it
against the wall, there's a force that your
fist is applying to the wall because you're
trying to make both of these solids occupy
the same space at the same time and those
bonds between the different particles do not
want to slide past each other.
They want to hold on to its shape and hold
on to its volume.
Now it seems like you understand this aspect
and most everyone does because we interact
with this all day every day.
Whether I'm opening a door, or turning a TV
on, I'm applying a force on an object and
that object holds its shape.
However, in the next slide, we'll cover something
that might not be as intuitive simply due
to the fact that we don't interact with it
as much.
Or rather when we're interacting with it,
we don't consciously know we are.
Now let's about normal forces in a gas.
Earlier we talked about a solid is something
that holds its shape and holds its volume.
A liquid is something that holds its volume,
but doesn't hold its shape.
Now here in a gas a gas also does not hold
its shape but what's different about a gas
is that a gas does not hold its own volume.
We often hear that a gas expands to fit the
room that it's in.
So this makes gases a little bit different.
We have to make sure we understand what's
going on with the gas, especially when talking
about the force that a gas exerts on objects.
So let's talk about pressure, both at a small
scale and at a large scale.
At the small scale, the micro scale, if we
look here at the top right.
Gas has a bunch of particles that are bouncing
around and colliding with each other but it's
also colliding with the objects that are exposed
to that gas.
So if I had a pressure tank that also had,
I don't know, let's say someone dropped their
keys inside the pressure tank and it got pressurized.
That higher pressure in the pressure tank
is not only applying this force onto the container,
right onto the pressure tank, it's also applying
it on to the keys that are inside the tank.
This is because the individual particles of
the gas are bouncing off not just the walls
of the tank but also the objects inside the
tank.
Now when these particles bounce off the objects
that it comes into contact with, it's applying
a small force onto that object.
And that object, of course, has its reactionary
force where pushing back onto the particle.
Pressure is the average that the particle
exerts in this collision taken over a certain area.
For instance, if I had a three inch by three
inch piece of steel inside a pressure tank
the pressure on that piece of steel would
be the average of all the individual forces
of all the individual particles hitting that
piece of steel.
This is why we use the term pressure when
dealing with gases and not force because we're
average and out over a specified area.
Now at the macro scale we usually use the
equation of state or the ideal gas law to
explain what the gas is currently doing, and
I have the equation there at the bottom: the PV=nRT.
So if we're trying to understand the pressure
of a gas, right the force that is exerting
on a certain area.
We have to also take into account the current
volume that the gas is occupying, V.
We have to look at n or the number of moles
(how much gas is in that volume at that time).
Then you have R which is the gas constant.
So depending on what the gas is.
Is it air?
Is it carbon dioxide?
Is it nitrogen?
And then, of course, T the temperature.
So to understand the force that a gas is exerting
on a specific area, the pressure, we have
to understand all of those other variables
as well.
That's why this is called the equation of
state, what's the state of the gas.
Now think of all this when talking about punching
air and trying to feel a force of it.
If you're in a room and you're punching air,
are you changing the volume of air in that room?
No, the walls of the room are stay the same.
Your fist is merely moving around in the air,
it's not really changing the volume of the air.
Granted there could be a little bit of negligible
factors with cracks and doors.
We're not talking about that.
Obviously, the punching is not changing what
gas is in the room.
And on a large scale you're not changing the
temperature of the gas.
So understanding that, I would ask what were
you expecting to happen?
You are trying to increase the pressure, the
force per area, that you felt on your hand
without changing the volume, without changing
the amount of gas, the type of gas, or the
temperature of the gas in the room.
Were you really expecting a force increase
on your hand, something that you would feel.
Now I'm saying force increase because there
is currently pressure in that room.
We call this atmospheric pressure.
That's the pressure we have here on the surface
the earth.
We are creatures living at the bottom of an
ocean of air and at the bottom of this ocean
of air has a typical air pressure of 14.7
PSI-a.
Now there's one other thing to consider when
talking about the pressure of a gas and that
has to do when you start adding movement to
the equation.
Whether that is the gas moving quickly past
a stationary object or an object moving quickly
through a stationary gas.
When you push on a gas and cause it to start
moving, you are aligning to some degree the
direction of travel of those individual particles.
And so what happens is more particles hit
the object in that direction of travel than
they are hitting stuff out of that direction
of travel.
Now remember we're talking 3D space here.
So you're increasing the velocity of these
particles in one direction but they still
have velocity in other directions.
Now you still have to consider how the other
particles are moving around the object as well.
So it's a little bit more complicated than
just thinking "well I increased velocity in
the X direction so I should see an increase
in pressure".
No, particles also flow around objects.
Now this whole study of how air flows around
objects, or the pressures developed on an
object in a moving gas scenario, is what we
call aerodynamics.
When an object is flowing through a fluid,
as an air, or this fluid is moving around
an object we're entering a complex flow field
type of a problem which often needs the flow
field solution.
This is where the Navier-Stokes equations
come to play and this is where we spend a
lot of times as aerospace engineers in aerodynamics.
What we try to do is we try and understand
a flow field around this object and understand
the local pressures on the surface of the
object.
Different parts of the object have a different
local pressure and so in reality what we need
to do to see the different forces on that
object is we need to, using vector calculus,
sum up the pressure around the object to determine
where the net or resultant force is on that object.
And then we could take that resultant force,
break it into a component that is acting along
the same axis as the flow direction right
we call that drag, or perpendicular to the
flow direction and we call that lift.
Drag being a force that is experienced by
the object that is trying to resist its movement.
"what if i for example in skateboard I have
a ball bowling ball let's say and I throw
it and i go backwards look when you are standing
on a skateboard and you are pushing a 15 pound
bowling ball that 15 pound bowling ball a
static inertia it means it wants to stay set
it doesn't want to move so when you are pushing
that you're pushing yourself back" Okay, first
off it's not "static inertia."
It's just inertia.
Inertia is an object's resistance to acceleration
due to the mass of the object.
This actually comes from Newton's first law
of motion which states that an object at rest
wants to stay at rest and an object in motion
wants to stay in motion unless acted upon
by an external force.
So what this means is that an object's velocity
wants to stay the same whether it's lost is
zero, because it's not moving, or whether
it's a positive value.
This means that to change an object's velocity
we have to apply an external force to accelerate it.
And inertia is the resistance of that object
to accelerate.
I mentioned this because whether an object
is stationary or moving its mass is usually
not changing and since inertia is just the
resistance to acceleration based on mass you
really aren't going to see a difference between
a static and a dynamic inertia.
And it's the reason why we just say inertia,
not "static inertia."
Now second off, this skateboard example is
actually a pretty common example of the third
law of motion.
In fact, I used a similar example in a video
I did for my rocket series.
Maybe I'll go ahead and throw a clip from
that video here for any of you who might not
have heard of this experiment before.
I went ahead and put together an example that
I'm hoping helps to clarify how the third
law motion and the second law of motion both
explain how a rocket produces thrust.
And to really give you an a physical example
of what's happening since it can be a little
hard to wrap your mind around at first.
Now, for this example, let's say it's Friday
night and you decide hey what better thing
to do on a Friday night then go down to my
local hardware store and buy a bunch of anvils.
Anvils, of course, are these very big massive
heavy tools.
So you go down to the hardware store.
You load up a shopping cart full of anvils
and the lines are busy so you decide to play
around for a little bit.
So you decide to go ahead and sit on the shopping
cart, pick up one of the anvils, and throw it.
Now, I know what you're thinking.
"This is totally what everyone does on Friday
night."
Now what's going to happen to you.
Let's take a look at it from a third law perspective
and a second law perspective.
From a third law perspective, we see here
on the left when I am throwing the anvil I
am using my muscles to exert a force on the
anvil.
This force that I'm exerting on the anvil
would be the action force.
And from the third law we know there is a
reaction force equal and opposite to the force
I exert with my muscles.
The idea being that if I'm pushing on the
anvil, the anvil is pushing on me.
And since I'm sitting on this cart full of
anvils, it's pushing on me and the cart and
all the anvils together in the opposite direction
as the force that I threw the anvil.
Take a quick second to think about it.
Obviously the anvil is gonna move backwards
because I just threw it.
What about me sitting on top of the cart?
Am I gonna sit still?
Am I gonna move?
Why am I gonna move?
How far am I gonna move?
Am I gonna move as far as the anvil?
Am I gonna move farther than the anvil?
Am I gonna stay still and the anvil is gonna
move?
To understand the motion that would happen
due to these reaction forces we actually need
to separate the objects, look at them individually
in a Free-body diagram to see what all the
different forces are acting on both objects.
Looking at the anvil, there's a weight object
that's pulling it down but we're just going
to neglect that for right now.
We're not looking in that direction.
We're looking at the horizontal direction.
If we look at the horizontal direction, this
action force that I applied to the anvil would
be pushing it to the right.
And the only resistive force to that would
be air drag, which is probably not going to
be that important.
So we're just going to ignore it and say that
it's so small we don't care about it.
To understand the acceleration of the anvil
to the right we use the second law of motion,
F=ma, and use this net force to the right
and the mass of the object and determine it's
going to accelerate to the right.
This is what we already knew.
It's pretty intuitive that if I throw it it's
going to be moving in that direction.
Now what might not be intuitive is what's
gonna happen to me sitting on top of this car?
We know from the third law that when I pushed
on the anvil, the anvil pushed on me and the
card and everything in the cart.
So what we have is this force that is pushing
on us to the left.
We do, in real life, have some forces that's
going to resist this force.
For instance, we're gonna have friction in
the bearings and wheels.
Since we're talking about rockets we're not
really gonna have these wheels and the ground
and all that friction to deal with.
So we'll just ignore it here in our example.
So really I'm having this force that is pushing
me in the cart to the left, with nothing really
resisting it.
I mean I got some air drag but like we talked
about before for this instance it's very small.
Since there is a net force on me in the cart,
me in the cart are going to accelerate to the left.
Now when I asked you how far I was going to
go, if I moved, I was really hinting at this
idea that there's a difference in mass between
the anvil and myself and the cart and all
the other anvils I have in there to purchase.
So the anvil is gonna go a lot farther than
I am in my cart but I'm still gonna move some.
Now what's gonna happen if I pick up another
anvil and throw it?
The anvil is gonna fly backwards and it's
it essentially going to be pushing me forwards
a little bit at a time.
Since I loaded up and I've got a handful of
anvils in my cart, if I pick one up and throw
it, pick one up and throw it, pick one up
and throw it, I can essentially start propelling
myself forwards by throwing the anvils backwards,
right, by forcing this mass to the rear.
And this is the idea of how a rocket produces thrust.
So when a rocket is burning and creating this
jet of combustion gasses, it's throwing this
mass of gas backwards.
Now the mass of the gas isn't very big, there's
not a lot of mass there, but the rocket is
producing thrust because it's throwing it
at very high velocity backwards and as it's
burning it's throwing more and more and more
and more.
So it just keeps throwing, throwing, throwing,
throwing this small amount of mass at high
velocities rearward.
And so that's creating a huge momentum.
Momentum is mass times velocity.
Its creating this huge momentum, or force
backwards, and due to Newton's third law we
know that there is a reaction force of the
same momentum pushing the ship forward.
And that is what we call thrust.
Now there's something else to notice in this
example.
As I pick up an anvil and throw it the mass
of me plus the cart plus everything in the
cart is actually decreasing as well.
And we'll probably talk about that in a future
video and maybe even a little bit in the in
the video where we go over the general thrust
equation.
Just keep that in the back your mind.
Hopefully now you have a better understand
of this experiment of this example.
The third law comes into play to describe
the interaction between you on the skateboard
and the big heavy object that you're throwing.
As you're throwing this object you have to
use your muscles and apply a force to accelerate
it and as you are pushing on it, it is actually
pushing back on you.
That's the third law it's describing the interaction
between me applying a force on another object
and that of objects applying a force on me.
Now for wanting to look at the motion of the
heavy object that we throw, or the motion
of me standing on the skateboard as I get
pushed back, then what we need to do is we
need to separate the two bodies, look at them
individually in a free body diagram (we're
trying to look at all the different forces
acting on me vs. on just the heavy object
that we throw).
As we look at the different forces acting
on the object, we can find out where the net
force is going to be.
We threw the ball, the net force was in that
direction so it accelerated that way.
However, the force it pushed on me caused
a net force on me that way which is why I
would accelerate the backwards.
This is the idea behind it.
Now I take issue with this part of your video
because it doesn't seem like you're completely
understanding the third law and that you're
somehow trying to use the first law to explain
the motion of you moving backwards.
Now maybe this isn't the case but the way
your video explains this example is that you
try and define that this heavy object has
what you call "static inertia" (right this
resistance to movement) and so you're pushing on it but it doesn't want to move so you move backwards.
You're pushing yourself on something that
doesn't want to move.
However, this is not how the example is actually
working.
We do this example both the heavy object moves
and you move as well.
That would be described by the second law.
The third law is just describing the interaction
between me and the heavy object in terms of the forces.
I apply a force on it, it has a reactionary
force that it applies on me.
"you are pushing yourselves back if you think
that the third law of motion works in these
kind of cases then you can just throw a pen
see if you go backwards when you are throwing
your pen throw a balloon throw a light object
yeah cool so you have a balloon and you can
push the balloon and see if you go back or
a ping pong ball it doesn't happen".
All right, at this point you either have a
serious misunderstanding of the laws of motion,
specifically the third law, or you're being
misleading on purpose.
I'm not exactly sure which one it is.
I want to give you the benefit of the doubt
but it's kind of hard right now.
Earlier you claimed that the skateboard example
worked because you were pushing against a
heavy object but now you're trying to claim
that it doesn't work on the light objects.
Could you provide me the weight at which the
third law no longer applies right?
When it is no longer a heavy object, it's
a light object so it no longer works.
What what is that weight to you?
And what's the physics behind why that weight
no longer works?
Now you are again operating under the faulty
assumption that you are applying the same
force on the light objects as you were the
heavy object.
Now we know that with Newton's second law,
force equals mass times acceleration, if we
get a lighter object in here that has a lot
smaller of a mass.
If you're wanting to have the same force you
have to compensate it for it with your acceleration.
So your acceleration is going to skyrocket
through the roof.
If you were trying to apply the same force
on the light object that you were on the heavy
object you have to accelerate it by a large
amount.
You might actually throw out your shoulder
before you're able to get this light object
to accelerate fast enough to achieve the same
force as you did on the heavy object.
This is actually why a heavy object is used
in the skateboard example because for a typical
throwing speed you have to exert a greater
force on a heavier object.
So it's going to exert a greater force on
you, causing you to actually move farther
on the skateboard.
With a light object you're not able to achieve
a high enough force to see as much movement.
What's interesting about rockets is that they
are not throwing a very massive thing backwards.
They are throwing a lighter object, a gas,
backwards but at such high velocity that you
get that high momentum.
You're getting a high force out of it because
you're throwing it very very fast again.
"the same thing when you are pushing your
car have you ever tried to when the car is
broken and you are trying to push it in the
beginning it doesn't move it's heavy and after
some time it just moves slower it got out
of that static inertia its now moving so its
easier to push it its not that difficult in
order to get this reaction you have to push
against something otherwise its not happening"
Again you're using the same term "static inertia"
but as we talked about before inertia doesn't
have anything to do about whether an object
is stationary or whether it is moving.
Now as long as the mass is staying the same
for an object, whether it's stationary or
moving, the inertia is going to stay the same.
Now you can move something out of its stationary
position by applying a force and causing it
to accelerate but you can't just push it out
of its inertia.
The mass will always be there.
Now there is another type of inertia out there
that we call rotational inertia.
This moment of inertia, or rotational inertia,
is what resists angular acceleration, right
rotational acceleration.
And that has to do with mass as well but it
has more to do with how the mass is distributed
around the spinning axis.
So you can have normal inertia, or rotational
inertia sometimes also called moment of inertia,
but there's no such thing as "static inertia".
Now I'm kind of curious why you keep using
"static inertia" and where you must have gotten
that term from.
Hmm...
Oh, no.
Oh, no, That's not good.
That's not good at all.
Now I'm going to go ahead and continue with
the video and I'll come back around to this
idea of pushing on nothing since this is at
the heart of his claim and we'll talk about
it in great detail towards the end of the
video.
And really it's the only argument he has supporting
his claim at this point and we'll tear it
apart towards the end of the video.
"this guy the reason it goes up is this high
velocity and hot gases that exited exhaust
of the rocket engine will push against the
ground first and then takes off and it goes
up the air down here becomes thinner but even
if it's thinner the speed of these gases will
turn that thin air into a barrier you know
when you are driving in the highway and stick
your hand out of the window and you feel this
pressure the faster you go the more pressure
you feel thats the same thing even if your
hand is small the speed is high the pressure
increases it becomes a barrier the same thing
here it pushes the hot gases and high velocity
gasses down even if its thin it still creates
a barrier out of it so as long as there is
air or thin air the rockets do work but then
it goes out in the vacuum of space where there
is nothing then its nothing you can push it
and nothing will happen" So the claim is being
made that air is going to turn into a barrier.
I would love to hear the scientific explanation
for how this barrier is made, what's it made
out of, at what speed does it made?
Is it not made for slower speeds?
Is it only high speeds as he's suggesting?
There are lots of questions about this idea
of a barrier but not a whole lot of science behind it.
As we learned previously in the video, gasses
allow their particles to move past each other.
So since the exhaust coming out of the rocket
and the atmosphere into which the exhaust
is being expelled are both gases, and we know
that gasses allow particles to move past each
other, I would really love to know what this
barrier is he's talking about.
Now it's true that the particles from the
exhaust and the particles from the atmosphere
are going to collide.
There's going to be a lot of collisions especially
with the mass flow coming out of the rocket
and the velocity at which it's coming.However
these collisions aren't forming a barrier.
I think I know where he developed this idea
of a barrier in his mind and it's really my
second contention with this clip you just
saw and that's the idea of sticking your hand
out the window of a car.
You see sticking your hand out the window
of the car is not really the same thing as
the exhaust gas being expelled into the atmosphere.
In the case of the exhaust we have one gas
being expelled into another gas.
When we stick our hand out the window of a
car we are now introducing a solid into a flow of gas.
Now when you sit your hand out the window
of a car your hand being a solid is going
to affect the flow of the air around your
hand.
This is the whole idea behind aerodynamics,
is understanding the flow that develops around
a shape when you're sticking into different
flows of of air.
In aerodynamics we would actually call this
a blunt body.
We've got this nice big ol' flat area facing
the oncoming flow of air.
So it's going to be very draggy.
So that force you feel on your hand is actually
the drag that's being developed because this
hand, this solid, is affecting how air moves
around the object.
So this pressure you feel in your hand is
the increase of pressure on your palm side
of your hand and the decrease of pressure
on the backside of your hand due to the way
that the air is flowing around your hand.
You can actually play with it a little bit.
If you bring it horizontal, you can actually
start increasing the angle of attack of your
hand or decreasing it and actually feel the
air pushing your hand up and down.
Really this is an aerodynamic situation.
There's not any weird barrier being created
of the gases.
My hand is a solid.
It is the barrier.
"but then it goes out into the vacuum of space
where it is nothing then it is nothing you
can push it and nothing will happen this is
easy to test actually look you can get a single
drone and just put it on the ground accelerate
it so it lifts up from the ground and hovers
at 20 cm" So normally I just leave a little
bit of the clip in before hand so you know
that I'm not leaving anything out.
However I left a little bit more in this time
just to give you a little laugh as he claims
that a rocket has to push against the air
to move.
And then he then pushes against the air and
says nothing nothing there's no force here.
But that's the same thing the rocket is pushing
against according to him so I just left that
in there for your enjoyment.
I think we left the science behind guys as
in this experiment he's trying to show how
rockets work in space by showing us an experiment
in the atmosphere not including rocket propulsion.
So the manner of propulsion is different and
the environment is different but this test
is supposed to prove something about that
propulsion in that environment having nothing
to do with either of them.
Yeah, this would be like me telling you "let
me show you how to make brownies in the oven
by making Easy Mac in the microwave."
Its just they have nothing to do with each
other.
Actually they're making me kind of hungry.
Maybe I'll skip this experiment and go make
me some mac and cheese.
It's got more to do with rocket propulsion
than this experiment does.
"its easy to test actually you can get a single
drone and just put it on the ground accelerate
it so it lift up from the ground and hovers
at 20 centimeters do not touch the accelerator
anymore just put the cardboard sheet under
the drone and just lift it up when lifted
up the drone starts coming up also and it
maintains the same 20 cm distance between
the bottom of the drone and the sheet and
when you take the sheet out you take it away
the drone just drops down hits the ground
and the hitting the ground has to do with
inertia" Again with the misunderstanding of
inertia.
The drone hits the ground because the lift
force generated by the propellers is not enough
to overcome the gravitational force of the
earth pulling on the drone.
This creates a net force downwards and so
the drone actually moves towards the ground.
Now it hits the ground even with the increase
lift due to the ground effect that we're going
to talk about here in a minute.
Even with that boost it's already accelerating
fast enough, it has enough momentum, that
it's not able to stop in time before hitting
the ground.
However, it is able to recover with that increase
in lift due to ground effect we're about to
talk about and balance itself out.
The inertia of the drone, since it was at
rest while it was hovering wanted to keep
it at rest or hovering due to the first law
of motion.
However, the net force of gravity according
to Newton's second law of motion is what actually
pulled it down to the earth.
"hitting the ground has to do with inertia
it hits the ground and comes up and maintains
the 20 centimeter distance so based on these
observations based on what I just showed you
pushing punching and the drone which i can
show you actually we can go outside and i
can demonstrate this its impossible for the
rockets to work in the vacuum of space it
just doesn't happen" Now remember that his
punching and his pushing showed a serious
lack of understanding of how gases work, the
pressure that's developed by gases in aerodynamics
of solids in gases, as well as his experiment
testing neither the equipment nor the environment.
"this just doesn't happen the third law of
motion happens when you apply your action
on something and that something can react
to you when there is nothing there is no reaction
simple as that yeah and the thing is many
people say that the rockets don't work in
the space because there is no air no you are
just misunderstanding it they are carrying
their own liquid fuel and they are carrying
their own liquid oxygen so they don't need
air thats not the problem the problem is this
pushing act you have to push on something"
Even though this guy has a lack of understanding
in a couple areas at least he understands
that a rocket brings its own oxygen and that's
why it's able to burn in a vacuum.
Now, believe it or not, there are some people
who think that you can't burn the fuel the
rocket fuel in a vacuum.
These people probably have never heard that
you actually carry oxygen with your fuel in a rocket.
So we've at least have to give this guy props
for that, that he understands that.
Though it's curious why he thinks we would
go to such great lengths to carry oxygen with
us if we never leave the atmosphere.
Hmm...
Maybe the rockets don't actually carry oxygen.
Maybe they have secret inlets where they stuck
air and from the atmosphere.
Maybe their rockets carry oxygen because they
are seeding the ozone layer why else would
they carry oxygen on board if they can't leave
the atmosphere?
Sorry, I caught the conspiracy bug there for
a second.
Whoo...
Let's keep going.
"the problem is this pushing act that you
have to push on something so you would say
that they don't move they cannot move up in
outer space when you are in a vacuum no this
doesnt thrust it doesnt produce any thrust
even if its like its producing its own fuel
it wouldnt move it wouldnt move at all as
i said you have to push against something
in order to feel that reaction and back here
is a vacuum now i mean everywhere is a vacuum
in space so there is nothing to push against
and done its just not happening so yeah we
can actually go outside and try the drone
thing so im not a good pilot so i have to
try and balance it first try our best ok here
we go so as you can see i'm not pushing the
gas anymore and we go up you see i'm not touching
the gas and there it comes down we go up and
here you go and the 20 cm it maintains and
then we go up again you see it needs something
to push against otherwise it drops yup as
simple as that based on this you can see rockets
cannot work in the vacuum of space its done
there is nothing you can say about this its
over" Nope, ground effect.
Oh, you wanted a better explanation than that?
To the chalkboard.
So let's talk briefly about ground effect.
Ground effect, as you can probably guess from
the name, would be the effect that the ground
has on your lift when you get close to the
ground.
The ground effect has a tendency to increase
the lift and decrease the aerodynamic drag.
This is due to an increase in pressure below
caused by the change in flow of the mass moving
through your propellers but it also reduces
the wingtip vortices.
These wingtip vortices are losses.
So by reducing these you are reducing the
losses that you normally experience.
Now this cushion effect is also something
that you can see in hovercraft where they're
blowing air underneath them to create this
cushion of air.
It's pretty similar to that.
Now, for your example, the cardboard, when
you hold it up underneath the drone, is acting
as the ground causing a ground effect situation.
So it's able to balance itself out, slightly
above the ground, because it has an increased
lift due to ground effect.
When you pick up the cardboard and you help
the drone rise up in the air because you're
holding this ground, this cardboard underneath
it, you're essentially moving the ground.
And you can easily see this is the case.
When you remove the cardboard, it leaves the
ground effect state goes into a normal flight
situation.
But the lift isn't enough to overcome the
weight of the drone and so it falls back down
out of the sky.
So as you can see here on the left when I
have the normal lift that the propellers are
generating added to this extra boost that
the ground effect is giving us it's able to
balance out the weight.
And so there is no net force.
There's no acceleration.
It's able to hover where it's at.
However, you remove the cardboard out from
under it and it no longer experiences this
boost in lift due to ground effect.
So it's only left with this lift from the
propellers that it's generating which is not
enough to overcome the weight.
And so now we're in a situation where there
is a net force on the object and it's going
to cause it to accelerate in the direction
of this net force and that would be downwards.
So not only is this experiment not talking
about rockets, nor talking about vacuums,
but you're also misunderstanding what is actually
happening in your example.
So we reached the end of his video but I've
still got a couple more things to cover.
Essentially, his claim that rockets don't
work in space was backed by an incorrect understanding
of gases and gas pressure, an incorrect understanding
of aerodynamics, an incorrect understanding
of the laws of motion, as well as an experiment
that had nothing to do with rockets or a vacuum.
However, I want to cover a few critical issues
with the idea that a rocket pushes against
the atmosphere in order to develop thrust.
The issues we will go over will show why this
theory that rockets push against the atmosphere
fails to correctly model or correctly describe
the actual events, the actual phenomena, of
rockets and rocket propulsion.
The reason it fails to describe and model
is because it is an incorrect theory.
It is wrong.
It does not match the physical world.
Alright, let's go ahead and talk about the
first problem with this claim that a rocket
needs to push against the ground or the air
to move.
The claim is stating that the action force
would be the exhaust gas pushing on the atmosphere
and the reaction force being the atmosphere
pushing on the exhaust gas.
However, this leaves out a force that is used
to accelerate the exhaust gas.
The exhaust gas, of course, has mass.
It's gas.
It's an object.
It is not mass less.
So it's going to follow the laws of motion.
Now what we see is that this gas inside the
combustion chamber of the rocket has a relative
velocity of zero.
Now I'm saying relative because the entire
rocket vehicle, right the stuff that's wrapped
around this rocket engine, might be moving.
It might have a velocity and the difference
between the exhaust gas velocity and the vehicle
velocity is essentially zero.
Now as the gas flows out of the nozzle and
exits the rocket engine we see that this exhaust
gas now has a very high velocity.
So we see that there is a very big difference
between the velocity of the exhaust gas leaving
the nozzle and the velocity of the exhaust
gas in the combustion chamber.
Now we know due to Newton's second law of
motion, force equals mass times acceleration,
that if we have a mass, and the exhaust gas
is a mass, it's a gas, there are particles
and molecules and that has mass.
So if we have this mass that accelerates there
must have been an external force applied to that mass.
So we see that the mass of exhaust gas has
gone from a relative velocity of zero to a
relative velocity of far greater than zero.
There is some force that has been applied
to the exhaust gas to cause it to accelerate.
Now some will try and say well it's the pressure
of the gas.
Pressure as we've learned before is the normal
force that the gas exerts on another object,
not an external force moving the air.
What we have here is we have acceleration
of the mass of air.
There is an external force being applied to
the air causing it to accelerate.
Now the reason that it is left out of the
other theory, right this theory that a rocket
needs to push against the atmosphere or the
ground, is that if there is another force
taking place inside this rocket engine (causing
the gas to accelerate) then there must be
another reactionary force pushing back on
the engine.
And if that's the case that would be providing
thrust and "oh crap" now the rockets not pushing
against the atmosphere anymore.
Now that's why they try and leave this force
out or try and discredit say "well it's just
the pressure" not understanding that the actual
gas is accelerating due to an external force
being applied to it.
So let's look at what's actually going on
inside a rocket engine.
The rocket engine begins by converting the
fuels chemical energy into thermal energy
when it combusts the fuel.
We're burning the fuel and it's turning into
heat it's turning into pressure.
This thermal energy is then converted into
kinetic energy of the exhaust gas by the nozzle.
This nozzle is usually a convergent divergent
nozzle and it's going to have the effect of
reducing both the pressure on the temperature
and increasing the velocity of the exhaust gas.
Now the nozzle is what pushes on the exhaust
gas to accelerate it out the back.
And, of course, the the reaction is that the
gas also pushes against the the walls of the
rocket and that's what produces thrust.
Now there are those people who want to claim
that the exhaust gas is just somehow leaking
out due to its pressure.
Or sometimes you'll hear this idea of a "free
expansion" of the gas.
The problem with both of those is that they
are forgetting the nozzle.
The nozzle is a flow restriction.
You can't have free expansion if you're having
a flow restrictive device in the flow and
the nozzle is a flow restrictive device.
It creates a choked flow condition where the
amount of mass that is able to flow through
it is regulated.
This flow restriction means that there's a
pressure build-up upstream in the combustion
chamber and that there's an acceleration and
a high velocity at the exit of the exhaust gas.
Due to this flow restriction, you cannot say that it is a free expansion and that the gas just leaks out.
And if it doesn't just leak out then you need
to have a reason why the exhaust gas accelerates
from zero to many times the speed of sound,
and that requires a force.
You need to push on that gas somehow and then
when the gas pushed back on you, you develop thrust.
Alright, let's go ahead and talk about another
problem.
And this problem is that the rocket and the
exhaust are traveling in the same direction
as viewed from a stationary observer on the
earth.
Now when talking about the relative velocity
that the exhaust leaves the rocket, the effective
exhaust velocity, is really when it comes
down to it driven by the choice of the chemicals
used in combustion.
If you choose something like black powder
it's gonna be around 2,000 meters/second.
Versus if you're using like the liquid oxygen liquid hydrogen it's gonna be around 4400 meters/second.
Now there might be some slight variation due
to the manufacturing of the rocket engine
but these values are pretty typical and they
don't really fluctuate that much.
Which is why it's used a lot of times, with the mass ratio, to do some back of the envelope calculations.
You can think of the mass ratio as the ratio
of the mass of the rocket when it's fully
loaded versus when it's got an empty tank.
Now both the effective exhaust velocity and
the mass ratio are used to create the plot
that you see here on the left.
This is using the Tsiolkovsky rocket equation.
And so we're able to calculate what the rocket
vehicle velocity will be based on the effective
exhaust velocity and the mass ratio.
Of course, if we use the final mass ratio
we can determine what the final velocity of
the rocket will be.
So let's look at a quick example.
If we take the space shuttle that has a mass
ratio of about 16 and because it's using liquid
oxygen liquid hydrogen it's gonna have an
exhaust velocity around 4400 meters/second.
So if you look at it on the chart, I marked
it there with a star.
It means that the final velocity of the Space
Shuttle is around 12,000 meters/second.
That's pretty dang fast.
So what does this look like to someone who
is just standing on the earth?
So if the rocket were to zoom past our stationary
observer, let's say it's traveling from left
to right, the stationary observer would see
that the rocket was traveling at 12,000 meters
per second past him.
The effective exhaust velocity is 4400 meters
per second out the back of the rocket.
This is a relative velocity.
Its relative to the velocity of the rocket
engine.
Which means that if the rocket is traveling
to the right 12,000 meters/second and the
exhaust has a relative velocity of 4,400 meters/second
to the left.
In reality as the gas exits the nozzle it's
going to be traveling to the right at 7600
meters per second.
That means to a stationary observer both the
rocket and the exhaust coming out of the rocket
are traveling to the right.
Now if we were to go back to the punching
example, imagine first placing your fist on the wall.
Not punching the wall, just placing your fist
against the wall and then quickly pulling
your fist back.
How much force did you feel that your fist
exerted on the wall?
In reality you shouldn't feel any because
it's going the wrong way.
Before we were able to apply a force to the
wall, because we were punching into the wall
but as we punch away from the wall we're not
able to apply a force on the wall.
So the problem, and my question to you would
be, if both the rocket and the exhaust are
traveling in the same direction as observed
by someone just standing on the ground then
how is the exhaust pushing on the atmosphere?
The problem is that the exhaust velocity is
going in the wrong direction to be applying
a force to the atmosphere.
So if it's going in the wrong direction and
is unable to push on the atmosphere the atmosphere
won't be able to push on them.
There's no action force so there can't be
a reaction force.
And so this creates a problem if you think
that it's pushing against the atmosphere or
against the ground.
Since they're traveling in the same direction
you're losing your action force.
Now there are some other flat-earthers, or
conspiracy theory people, we're saying that
it's not possible for the rocket to travel
faster than the exhaust that comes out of it.
There's a video I saw recently on YouTube
that was making this claim.
I'm gonna go ahead and cover that in my next
debunk video.
So stay tuned for that.
Now another problem has to do with the exhaust
speed versus the speed of sound.
But before we talk about the problem let's
just have a quick refresher on the speed of sound.
Sound is actually a pressure wave that travels
through the air.
This pressure wave actually acts on our ear
which is why we're able to hear things.
And that wave actually has a speed at which
it can travel through air, a maximum speed.
It has a speed limit.
The speed limit is called the speed of sound.
It is the maximum speed that a pressure wave
can travel through air.
We often call this Mach 1 where the speed
of the pressure wave matches the speed of sound.
The speed of sound depends on the type of
gas and the temperature of the gas as we see
in the speed of sound equation here.
Speed of sound is equal to the SQRT(gammaRT).
When talking about rockets, rockets can either
be in a subsonic condition, a sonic condition,
or a supersonic condition.
If we looked at a stationary rocket, if it
would send out pressure waves, we would see
that the pressure waves would just travel
outward from the rocket traveling equal distances
in all directions since the rocket is stationary.
At Mach 1, or the velocity of the rocket divided
by the speed of sound is equal to 1, meaning
that both the velocity of the rocket and the
speed of sound are the same.
This means that the rocket is traveling in
one direction at the same speed that the pressure
waves that it is creating are also expanding
out into the atmosphere.
If you think back to the kinetic theory, where
gas is just a bunch of particles that bounce
off of objects, something traveling at the
speed of sound means that when a particle
comes and bounces off of an object both the
object and the particle are traveling at the
same speed in the same direction after the
collision.
This has the effect of making the pressure
waves stack up against each other as the exhaust
gases expelled from the rocket.
This stacking up of the pressure waves is
going to create a sharp discontinuity between
the air upstream, which hasn't seen the object
yet, and the air downstream, which has seen the object.
This is what we call a shock wave, this stacking
up of the pressure waves.
Something similar happens when you travel
faster than the speed of sound.
If you think back to the kinetic theory if
a particle of air bounces off an object the
object is actually traveling faster than the
particle when it bounces off.
So you're still going to be seeing some of
this stacking up up the pressure waves and
we do see some oblique shocks start to form.
However, something very interesting happens.
Now normally, because the speed of the object
is not traveling faster than the little particle
that bounces off of it, the particle that
bounces off of it is able to transmit information
about that object upstream of the object.
So this is why we would see the flow start
to move its shape before the object actually
interacts with it.
However when you start going above the speed
of sound then the object is traveling faster
than those particles can transmit the information
upstream and this is why you develop very
hard very dramatic shocks.
So let's go ahead and start looking at how
this could pose a problem.
Alright, so according to your claim the exhaust
gas leaves the rocket pushes against the atmosphere
or the ground and then the ground or atmosphere
then pushes back against the exhaust gas and
that pushes the rocket forward.
However, one of the big problems with this
is how is the force that the atmosphere or
the ground is applying on the exhaust gas
being transferred to the rocket.
The exhaust gas isn't bolted down or taped
or glued to the rocket.
So the force that the atmosphere or the ground
exerts on the exhaust gas must also be passed
from the exhaust gas to the rocket.
However, there is a big problem with this.
You see the exhaust gases are exiting the
rocket at a Mach number much greater than 1.
So the exhaust is traveling much faster than
the speed of sound.
The speed of sound of course being the maximum speed at which a pressure wave can be propagated through air.
So this means that the exhaust is leaving
the rocket faster than a pressure wave can
travel through air.
If the object is traveling faster than the
speed of sound that means the object will
be traveling faster than the fastest possible
speed that that particle can bounce off the object.
So the gas is just travelling too fast to
allow pressure to be transferred up stream.If
the exhaust is exiting at greater than Mach
1, to the right, and the fastest that the
atmosphere can push on to this exhaust gas
is the speed of sound going to the left that
means that this pressure cannot travel upstream.
You can think of this as a fish trying to
swim upstream but the river is flowing fast
enough that it's just washing the fish downstream.
The fish can only swim so fast but since the
river is moving faster than the fish can swim
the fish is getting swept downstream.
The same thing is happening in the exhaust.
The effect of the atmosphere on the exhaust
gas, as long as those exhaust gases are traveling
faster than the speed of sound, cannot travel
upstream fast enough before they are swept downstream.
This means that even the next atom over after
the exhaust leaves the nozzle cannot affect
the next atom upstream before it is swept
downstream in the exhaust gas.
This means that once the exhaust gas leaves
the nozzle it can have no effect on the rocket.
The exhaust gas is traveling too fast.
And so what this means is that even if the
ground and the atmosphere were pushing against
the exhaust gas, the problem is that the exhaust
gas that is expelled from the rocket is traveling
too fast to be able to make that force push
on the rocket.
And so the rocket is unaffected by the exhaust
gas after it pushes it out the nozzle.
And let me just go ahead and add this on here.
The actual effect of the atmospheric pressure
on the rocket is that it decreases thrust.
If you look at the general thrust equation,
you'll see that thrust is developed primarily
by the mass flow being expelled out of the
rocket at a certain velocity.
However, there might be a pressure differential
between the exhaust at the exit and the atmospheric pressure.
Depending of course on that pressure differential,
the atmospheric pressure actually wants to
decrease the thrust.
So not only is the atmospheric pressure not
producing thrust, it's actually hurting the
thrust that is produced.
So it's the exact opposite of the claim that's
being made.
So I also have another question for you: "How
high is space?"
Now something that's not really well understood
or heard by the general population is that
the definition of where space begins is not
universally accepted.
There are different heights at which space
begins depending on what definition of space you use.
For instance, the US military and NASA use
a height of 50 miles as the starting point of space.
So anyone who goes above 50 miles is deemed
an astronaut by them.
Now 62 miles up is where a lot of the international
definitions come in, right the definitions
that you would see in international treaties.
This comes about by the Kármán line where
it's the calculated altitude at which you
would have to travel faster than the orbital
velocity to achieve lift using wings.
At which point wings would be useless because
you're traveling fast enough to be orbiting the earth.
So if that's your definition of space, then
space begins at 62 miles up.
A 2009 study by the University of Calgary
was looking to determine when the atmospheric
winds, or the effects due to this atmospheric
wind, are overcomed by this idea of the solar
wind or rather when the effects of space overcome
the atmospheric winds.
And they determined that that's at about 73
miles up.
If you want to define space as being where
you completely escape Earth's atmosphere,
right you are no longer in air no matter how
thin it is, you have to go up to 600 miles.
Now keep in mind the International Space Station
is up at you know 250 to 270 miles or whatever it is.
The Hubble Space Telescope is up above 300
miles, like 350-360.
You'd have to go another 300 miles past that
to escape the Earth's atmosphere where you're
out of the air completely no matter how thin.
So my question to you is where does your space
begin, and I think this is a pretty valid question.
You're claiming that rockets push against
air when they get higher up and that eventually
they'll reach a point where the air thins
out so much that they're not able to push
anymore on the atmosphere.
And this is really the secondary question
where the primary question is "What is the
maximum altitude a rocket can reach according
to your theory?"
"When does the atmosphere become too thin
that this 'barrier' can't be formed or there's
no longer something to push against?"
Let's see the math.
Show me where rockets can no longer work and
why they can no longer work due to the atmospheric
pressures versus the the pressures in the
rocket, the velocity of the exhaust gas, and
the temperature of combustion.
Let's see some principles of physics and science.
Let's see some math.
Let's see some models.
Let's see some equations.
Let's see some numbers.
Alright, that's the end of my video.
This was a new format, a new type of video,
that I've done.
I'll go ahead and throw it in the comments.
Let me know what you thought.
If you liked it let me know and maybe if there's
another video you want me to review/debunk.,
Other than that check out the other videos
on my channel.
My channel is dedicated to aerospace engineering
and helping those who are, or wish to become
aerospace engineers, take their skills to
the next level.
So go ahead and subscribe if you're one of
us AE guys or want to be one of us AE guys.
Thank you.
Hope you enjoyed the video.
I'm afraid I have bad news.
With these kind of grades, I really can't recommend that your child and move on to the next grade.
I'm afraid we're gonna have to hold them back
a year.
