Author Topic: Space propulsion  (Read 3570 times)

Offline vikram_gupta11

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Space propulsion
« on: 10/18/2019 06:01 am »
As per sketch a person is standing on a roller skate and the skate has two springs.
The person is stretching the both springs ( A&B) by using both hand.
But suddenly remove his hand from spring B.
The spring A is still stretched.
Now I would like to know that the roller skate should move forward as every action has reaction??
If it works then can we use this mechanism for space propulsion?

Offline Stan-1967

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Re: Space propulsion
« Reply #1 on: 10/18/2019 06:18 am »
.... can we use this mechanism for space propulsion?
No

Offline vikram_gupta11

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Re: Space propulsion
« Reply #2 on: 10/18/2019 06:36 am »
Why??
It will not work as a one time mechanism.
Each time the force will be increased.
At initial point if 1 Newton force is applying on both springs then the spring B will react with 1 Newton force.
But second time the force will increased .
Now applied 2 Newton force or equal force it will again move forward.
In this way just apply equal force on both side but remove the force from only spring B and skate will move forward.
I know that a point will come where the springs will be not stretched then just cancel both force or remove the hand from spring A and B at a time.
Now again start the same mechanism.
So why it cannot work???

Offline 1

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Re: Space propulsion
« Reply #3 on: 10/18/2019 06:48 am »
Movement of any one part of your system will be countered by a simultaneous opposite movement of another part. The skate, viewed by itself, can appear to move; but the complete skate-springs-person system will not. Stretching and releasing springs can only change the placement of individual pieces of your system. The center of mass of the system as a whole will not change.

Offline vikram_gupta11

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Re: Space propulsion
« Reply #4 on: 10/18/2019 06:50 am »
But it works on the earth and as far as I know if this mechanism works on the earth then it must work in space also as there is no need of medium for this kind of mechanism.

Offline 1

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Re: Space propulsion
« Reply #5 on: 10/18/2019 07:19 am »
It works on Earth because you can push off of the Earth itself thanks to the fact that there's no such thing as a friction-less surface. This gives the illusion of net movement because the corresponding opposite movement of planet Earth is immeasurably small. In open space, you don't get this option. So long as your setup is truly isolated, the only way to get movement is to break off a piece of your setup and throw it.

Offline vikram_gupta11

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Re: Space propulsion
« Reply #6 on: 10/18/2019 07:33 am »
But medium is not needed for this kind of mechanism.
In this mechanism pushing off earth is not a matter.
If I fixed a wheel under a rocket and it moves horizontal lly on the earth then ?

Offline 1

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Re: Space propulsion
« Reply #7 on: 10/18/2019 07:46 am »
But medium is not needed for this kind of mechanism.
In this mechanism pushing off earth is not a matter.

Yes, it is. Your system has wheels, and wheels are not frictionless. This is your misunderstanding. Like it or not, your system pushes off of the Earth.

Put this thing in open space, and it will never move.

Offline ChrisWilson68

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Re: Space propulsion
« Reply #8 on: 10/18/2019 08:26 am »
But medium is not needed for this kind of mechanism.
In this mechanism pushing off earth is not a matter.
If I fixed a wheel under a rocket and it moves horizontal lly on the earth then ?

Hi Vikram,

You have a mental model of how springs work and how forces work.  That model is intuitive based on what you see on Earth.  But that model is incorrect.

Don't feel bad about it.  Pretty much everyone on Earth got it wrong until the 1600s.  Then some people did very careful experiments.  These experiments take some work because on Earth friction really confuses things greatly.  It takes a lot of care to minimize or account for friction.  Issac Newton finally did it correctly and worked out the fundamental laws of forces and motion.  Today we call these Newton's laws.  One of those laws is conservation of momentum.  This law makes it immediately clear that your idea for space propulsion can't work.  It only seems to work on the surface of the Earth because friction is making it work by some non-obvious interactions.

The story of Newton's laws and how they were discovered is fascinating.  I highly recommend you take a good introductory physics class, which will teach you about them.

Offline mlorrey

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Re: Space propulsion
« Reply #9 on: 10/22/2019 11:54 pm »
this "push fast pull slow" model was the idea behind the Dean Drive and many other ideas by independent inventors with insufficient physics education. The problem is that when you time average all the forces, action and reaction, you still wind up with zero net thrust. The only way to use this technique propulsively is if you can change the mass of your vehicle between accelerations, so you push heavy, pull light, push heavy, pull light. This describes the impulse term of Dr Jim Woodward's Mach Effect equation, which is a straightforward derivation of general relativity. The real problem is, how do you change the mass of an object without tossing it overboard and eventually running out of mass to toss overboard?
« Last Edit: 10/22/2019 11:55 pm by mlorrey »
Director of International Spaceflight Museum - http://ismuseum.org
Founder, Lorrey Aerospace, B&T Holdings, and Open Metaverse Research Group (omrg.org). Advisor to various blockchain startups.

Offline vikram_gupta11

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Re: Space propulsion
« Reply #10 on: 10/23/2019 08:04 am »
I have a device and it's getting momentum.it means it's mass is being increased.

Offline Ixokani

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Re: Space propulsion
« Reply #11 on: 10/23/2019 01:43 pm »
I have a device and it's getting momentum.
Because static friction (in the wheels of your skate) is preventing movement during slow extension of your springs, but not during the fast retraction. There will be no such friction in space. You'll just be moving back and forth in place.

it means it's mass is being increased.
No, no it's not, don't be silly.

You have variation on the Dean Drive.

Offline Pete

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Re: Space propulsion
« Reply #12 on: 11/01/2019 11:25 am »
I have a device and it's getting momentum.it means it's mass is being increased.
You need to get one of two things:

either
A) multiple Nobel prizes and multibillion dollar contracts for voiding most of known laws of physics
or
B) Remedial high school physics and mathematics classes.


It may take some smooth talking to convince the world that case (A) takes precedence over case (B)

Offline rakaydos

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Re: Space propulsion
« Reply #13 on: 11/04/2019 04:52 pm »

Offline Iggyz

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Re: Space propulsion
« Reply #14 on: 12/17/2019 11:52 am »
Similar propulsion ideas can be found on YouTube e.g.

It seems also to work on earth. Very few think it will work in space.

 

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