What does a rocket push against in space?

originally posted by: charlyv
a reply to: buddha

"Every action has an equal and opposite reaction."

"Every action has an equal and opposite reaction."

Nice job, correct answer, and nothing else need be said.

Ding, Ding, Ding.

I mean this in the nicest possible way, but if those eight words don't set the proper bits for the OP, them you need to consider the possibility that the answer to your question, and Newton's Laws may just be beyond your understanding.

originally posted by: roadgravel
Wow. Is this going to be rockets in space are actually a hoax?

No. But it might lead into the "we've never gone beyond lower-Earth orbit" theme.

originally posted by: buddha


my point is a rocket in earth atmosphere
has some thing to push against.
But in the vacuum of space you have Nothing to push against.
Only the Gas the rocket pushes out the back!
So all the weight of the rocket is pushing against a Tiny mass of gas.

Please comment, I would like to know!

As a scientist, can you explain how the gas burns when there is no air?

a reply to: buddha

you raise an excellant point

originally posted by: carewemust

originally posted by: buddha


my point is a rocket in earth atmosphere
has some thing to push against.
But in the vacuum of space you have Nothing to push against.
Only the Gas the rocket pushes out the back!
So all the weight of the rocket is pushing against a Tiny mass of gas.

Please comment, I would like to know!

As a scientist, can you explain how the gas burns when there is no air?

Rockets bring their own oxygen in the form of an oxidizer that is carried in a separate tank to burn with the fuel.

4 pages - to address the most fundamental scientific illiteracy - the mind boggles

originally posted by: ignorant_ape
4 pages - to address the most fundamental scientific illiteracy - the mind boggles

I have become very disillusioned with this site of late. The level of scientific illiteracy seems to be higher than it has ever been before.

originally posted by: AngryCymraeg

originally posted by: ignorant_ape
4 pages - to address the most fundamental scientific illiteracy - the mind boggles

I have become very disillusioned with this site of late. The level of scientific illiteracy seems to be higher than it has ever been before.

Science is a conspiracy against religion and we must protect Muslims, the snowflakes said so. How dare Science define anything which does not fit with their understanding of things.

By using Newtons Law you are offending those who honour the air particles.

a reply to: buddha

Your belief that the rocket pushes against the air, or ejected exhaust, behind it is incorrect.

The thrust developed in a rocket engine is not based on a surface to push against. When you ignite the fuel in a rocket engine it expands outward in all directions. However, the only path it can follow is out the exhaust. The rocket engine is being pushed from inside by the rapid expansion of the burning fuel. It is pushed in every direction except out the exhaust where there is no resistance. The only direction of thrust without opposition is forward - opposite the exhaust. Once the gas exits the rocket engines venturi it is no longer part of the equation. The rocket does not push against it - or anything else. It is pushed forward by pressure inside the rocket engine itself.

The scenario you suggest is more suited to a propeller than a rocket. With no media to push against it develops no thrust.

originally posted by: buddha
Has any one calculated how much fuel you would
need to accelerate then decelerate to get to mars?

my point is a rocket in earth atmosphere
has some thing to push against.
But in the vacuum of space you have Nothing to push against.
Only the Gas the rocket pushes out the back!

think about that. when it starts it has nothing at All to push against.
and then as the gas builds up behind it. it will push against that.
So all the weight of the rocket is pushing against a Tiny mass of gas.

Please comment, I would like to know!

www.youtube.com...

It appears that after four pages, someone should have gotten enough information to know how rockets work.

In the interest of our continuing efforts to "DENY IGNORANCE" I have posted the link above in order to help in this matter as much as I can.
If some one has an interest in a subject, I think it would be "normal" for them to do a little research before asking that the information be spoon fed to them by others.
If this is not sufficient, I hope the OP will then move on to a subject which is not beyond their intellectual grasp.

a reply to: buddha

why don't you refer to an object that's already in space that uses rockets to adjust its orbital height, you can check its mass and its speed and the maneuvering thruster's force

Use the international space station as an example and calculate it for yourself.

You can find out its mass, its speed , its orbital height etc

but yeh newtons third law of motion

a reply to: AngryCymraeg

I'm disillusioned by all the intellectual superiority complexes that everyone seems to have developed , you know chastising people for not knowing something you do! (not you in particular)

but there is always an air of "imagine not knowing how rockets work, the shame , its basic rocket science" (apply that to any subject)
many users on ATS are quick to rub others noses in it simply because they are ignorant to the subject
but ignorance from lack of knowledge and understanding is being treated as a crime , instead of someone who just wants an answer from someone more knowledgeable instead people seeking answers are treated with disdain for simply wanting to know the truth from a community they like.

Instead its, "god sake cant you google , or use search function."

whatever happened to just being nice and giving your opinion or facts without having to berate the person asking
or treat them as if they are an idiot for not knowing.

I understand its no one's job to teach other people , but no one has to reply to anything they dont like , you can just leave the thread without commenting

a reply to: sapien82

That's true - I mean it is rocket science quite literally!

originally posted by: carewemust

originally posted by: buddha


my point is a rocket in earth atmosphere
has some thing to push against.
But in the vacuum of space you have Nothing to push against.
Only the Gas the rocket pushes out the back!
So all the weight of the rocket is pushing against a Tiny mass of gas.

Please comment, I would like to know!

As a scientist, can you explain how the gas burns when there is no air?

Solid rockets contain an oxidizer mixed in. Think of plastic explosive's everything it needs is all ready there no oxygen required. Liquid fueled often has a tank of liquid oxygen that's why if you ever watch a launcg you see ice form on the rocket. Liquid oxygen is at -218 degrees.

a reply to: sapien82

Your right not everyone is a rocket scientist. And in physics you quickly learn that things don't quite work the way you thought it did. Even the Germans when they were trying to make rockets made some huge mistakes. These were made do the lack of understanding of physics so they relied on trial an error.

And yes there was debates on if rockets would work in space.

When a person relies on asking someone for an answer then they fail to learn how to research and learn on their own. A combination of both is a better course of action.

a reply to: sapien82

It does get a little frustrating when back on page 1 the OP was given some explanations about Newton's Third law, and how rockets DO NOT push against anything to move, but the OP was still ignoring these explanations.

I agree that we need to be respectful to people who are trying to learn, but the OP needs to be able to respectfully take what is being explained to him and attempt to understand that explanation instead of ignoring it.

a reply to: sapien82

Actually yeah, just Google it - Here is what I go when I did:

How does rocket work in space - that is what I typed in, and look what I got...

Heck, it even includes how a rocket works without air...it includes everything to do with rockets in space for the layman.

a rocket or capsule in space, (traveling in a micro-gravity environment) must contend with the various micro-gravities which will cause changes in the space-craft's Angular Momentum (flight path)...
to gain speed in space, intermittent short bursts from the rocket engines will propel the spacecraft faster (there is little resistance and momentum will increase easily which is why there might be only 2 flight corrections in the typical flight-to-Mars voyage...)

there is also a thing called the Solar Wind composed of photons and stuff emitting from the Sun....
It is possible to deploy a huge Solar Sail in space and let the Solar-Wind push against the sail to propel a spacecraft so that rocket bursts to gain speed will not be needed at all... but fuels to steer the spacecraft: "pitch & yaw" controls, will still need to be carried on board for when the Solar Sail is jettisoned as the only propulsion system...
then the flight to beyond Mars will need a space Braking System if a desired, hidden, Earth like crater or zone on the planet is chosen as a landing site.


spacecraft have inertia, momentum, gravity, acceleration & breaking as the only forces to adjust or correct for...
the spacecraft has the original 17,000 MPH angular momentum it took to achieve orbit as the base... the rest of the flight is 'low cost' in comparison, but it ain't Free...
the micro-gravity of Earth-Moon-Sun all contribute to course corrections needed, also the Solar Wind will cause "Drag" on the spacecraft in almost infintesimal amounts~ but over the flight path of say 200 million miles that can cause an unwanted planet fly-by instead of a soft landing

a reply to: Soylent Green Is People

well patience always seems to work , you can lead a horse to water!