On earth or in outer space, the gases ignited resist against the rocket, just as the air from a leaf blower resists against the leaf blower, hence the
rocket is propelled forward, hence the leaf blower on wheels is propelled forward.
It's not rocket science, just logic and common sense which has been observed over and over again and again.
Just how dense do you think the atmosphere is? The fuel is pushing the rocket which has to have a velocity that exceeds gravitational pull, not the
bloody atmosphere. You do know that your own minuscule amount of energy you use to propel yourself along the pavement whilst walking easily overcomes
the resistance of the atmosphere in front of you? Please say yes.
Put your money where your mouth is: stand behind a rocket car for us. Obviously you won't get burned because the air behind the engine will protect
you. Air acts as a solid barrier for rocket exhausts to push against, so there's no possible way you'd wind up all crispy, right? Right?
Imagine you have a spherical container, and inside that container is highly compressed gas. Do you agree the gas is applying outward force on the
sphere equally in all directions?
Now, imagine we puncture a large hole into the bottom of the sphere. Do you agree that the compressed gas is no longer equally applying force in all
directions of the sphere? Do you agree that the gas is now applying more force to the top of the sphere than it is to the bottom of the sphere?
Do you agree the sphere would move up?
Initially there is pressure in the sphere. When you puncture a hole. The volume increases and the pressure inside the sphere decrease. Since pressure
decrease, the force applied on the walls decrease. So there is no overall movement unless the escaping gas meets resistance like an atmosphere
how is throwing marbles, a solid, the same as gas, a fluid, moving due to different forces applied. In your example the astronaut is pushing the
marble. In a rocket, pressure gradient force is doing the pushing, not the rocket
Nic, I'm being incredibly patient and benevolent here by still responding. I truly want to help you understand if you desire to learn. Please tell
me you don't, and you don't just believe some YouTube viral spreader (they make money from your clicks)
Firstly do you believe in science? do you believe there is a solar system? Do you believe space is a vacuum? Do you believe gravity works as agreed
by every physicist? And do you believe Earth is a sphere?
I will continue my explanation, but please answer in your reply if you don't believe ANY of the above! Thanks!
Problem#1: . MASS. Marbles and gasses both have MASS. Glass marbles are mostly SILICA, or SiliconDioxide, a simple compound. Gasses are simply
very small marbles, they are lightweight molecules, under a very powerful microscope you can see this.
1 marble might weigh a gram, but 1 gram of Hydrazine is no different, they both have 1gram of mass, and a rocket carries MILLIONS of grams of fuel.
GASSES HAVE MASS! It may be hard to imagine, and most gasses have little mass at normal sea-level conditions, however rockets normally store gasses in
LIQUID FORM. If you could hold Liquid Hydrogen or Oxygen, I feel like you'd understand better. In liquid form they are MUCH MUCH denser and maybe
you'd see why ejecting them from the back of any object would create a force.
Problem#2: You aren't really grasping what a pressure gradient is. Pressure gradients cause weather here on Earth. Very simply, when one area of air
gets heated or cooled differently than another, their pressure changes and the molecules of air tend to spill toward the lower pressure area.
Pressure is entirely RELATIVE, the Low pressure area doesn't need to be a vacuum, it just needs to be lower than the other region, and air will move
toward it. This creates WIND.
You would agree that WIND is a force yes ? Wind is literally a WORD we created to describe the force we can observe and feel acting on things like
our own bodies or blowing trees over.
A gradient-pressure itself does not move any spacecraft and NEVER HAS. "Gradient pressure" describes the situation when pressure is different in any
vessel or region, closed system or not.
Gradient pressure can CAUSE a force because of the MASS of the OBJECTS that move AS A RESULT of the different pressure states. Simply put, gradient
pressure moves GAS, gas movement creates force. Combustion further accelerates the gasses, creating additional force.
I'm not being sarcastic here, do you know of the word gradient in other uses? Search Google images for "gray gradient" and you'll see what the
gradient tool does in draw/paint programs. A gradient just refers to a difference in concentration of something, paint, gasses, soil, anything. In
the Google image search, there is full gray, fading to zero gray (creating a fade to White).
A rocket travels in space by ejecting anything of MASS in a direction to create a reactive force in the opposite direction.
You asked me earlier how the rocket would expel the bowling balls, the simplest answer is springs, exactly like a spring loaded pellet gun. A spring
stores potential energy, just like pressurized gas does.
You seem to believe gas does not have Mass, but have you never used a CO2 pellet gun?
Also on the topic of guns, since you seem to believe rockets much push off AIR to move forward, tell me what makes a revolver or a shotgun kick back?
The AIR resistance in the barrel??? NO, the kickback is caused by the BULLET leaving the firing chamber at rapid speed.
EXACTLY THE SAME as GASSES rapidly leaving the rocket. Gasses might be low mass, but Force =M*a, so you simply accelerate it very fast
There is also a neat little side effect that combustion ALWAYS creates H2O, and when water is heated it expands to roughly 1000x it's volume. On the
ground initially this does help provide a little extra lift, but once the rocket is traveling fast the steam is quite far behind the rocket nozzles.
When stationary in a vacuum the steam might help a bit also, but I'm not really sure on that.
Also one last thing, since it definitely seems like you are having a hard time with the mass of gasses, you need to understand it takes a LOT of fuel
to power rockets. Like a whole freaking LOT. One of my grandfathers helped develop SOLID fuel for this very reason, because density is very
important when trying to store large quantities of combustible material. My other grandfather worked on the Redstone program.
Last question real quick, I just thought of this since I remembered my grandpa's work on solid fuels:. Do you believe a solid fuel rocket would work
In the video above you can clearly see the tiny Walmart rocket engine create forward thrust in a vacuum.
edit on 11-5-2019 by 8675309jenny
because: Formatting and typos
So you agree that pressure gradient force moves the gas. So there is no opposite force In the rocket because it was pressure gradient force that
provides the momentum, not the rocket.
You're clearly trying to win something here. There's nothing to win, other than an understanding of how rockets DO move in space. It's a fact. They
do move in space, several people in my family have worked at Kennedy Space Center and Goddard. I just watched the second Falcon Heavy launch, and saw
the first also, both in person up close with my own eyes, as well as watching Shuttle launches my entire childhood.
My only aim here is to help you understand where you may be misunderstanding physics.
Now please answer the questions I directly asked you, or I will not reply to this thread again.
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