Move Mass in Space: How Much Pull?

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Discussion Overview

The discussion revolves around the concept of accelerating a large mass in space, specifically a one million pound rock, to achieve a continuous acceleration of 1g. Participants explore the implications of this scenario, including the forces required, the nature of propulsion, and the feasibility of such a drive system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the definition of a "million pound rock," noting that pounds measure weight and not mass, which leads to confusion about the local gravitational field.
  • There is a discussion about the requirements for achieving 1g acceleration, with some suggesting that it could be achieved through a constant applied force, while others argue that it implies a need for increasing acceleration over time.
  • One participant proposes that the drive system would not function like a traditional rocket, suggesting it would "pull" rather than "push" the mass, and emphasizes the need for a significant power supply.
  • Concerns are raised about the feasibility of the proposed propulsion method, particularly regarding the absence of exhaust and how thrust would be generated without it.
  • Some participants express skepticism about the scientific validity of the ideas presented, with one suggesting that the thread lacks supporting physics and should be closed.
  • Others engage in light-hearted banter regarding the nature of vacuum and propulsion, indicating a mix of serious inquiry and humor in the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the feasibility of the proposed propulsion system or the definitions and assumptions surrounding the mass and acceleration. Multiple competing views remain, particularly regarding the mechanics of thrust generation and the scientific grounding of the ideas discussed.

Contextual Notes

Limitations include unclear definitions of mass versus weight, assumptions about gravitational fields, and unresolved questions about the mechanics of the proposed drive system. The discussion also reflects varying levels of understanding and communication among participants.

Who May Find This Useful

Individuals interested in theoretical propulsion systems, physics of motion in space, and speculative engineering concepts may find this discussion relevant.

marmstrong941
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This is not home work right off OK
If there was a million pound rock in space how much pull (not a rocket pull) in pounds would it take to get it to 1 gee inlets say in a hour or less?
 
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I'm not sure you really mean 1g here since this is an acceleration.
 
What do you mean by 'a million pound rock'? Pounds is an (archaic) measure of weight (or, more generally, force), and the weight of an object is defined as its mass multiplied by strength of the local gravitational field. You haven't specified what the local gravitational field is.
 
andrewkirk said:
What do you mean by 'a million pound rock'? Pounds is an (archaic) measure of weight,
Clearly he meant mass.

If metric is your preference, let's assume, for round numbers, the rock masses 500 metric tons.

andrewkirk said:
You haven't specified what the local gravitational field is.
He wants 1g of acceleration. There is no local gravitational field.marmstring, the issue here is that you've specified two criteria:
- you want 1g acceleration, you could have that from the get-go with a given applied force.
- but to have it reach 1g acceleration after an hour, means you're talking about an increasing acceleration, from 0 up to 1g over an hour.

Normally, you'd specify either an acceleration of 1g, or you'd specify a speed you want to reach after one hour.

Can you clarify?
 
Ok sorry a Million pounds on Earth and one gee it would have to stay at one gee
 
marmstrong941 said:
Ok sorry a Million pounds on Earth and one gee it would have to stay at one gee
OK, that a 454 metric ton rock. Can we round to 500?
You want 1g continuous acceleration.

Simply F=ma

where
m=5*105kg
a = 10m/s2.
 
marmstrong941 said:
Ok sorry a Million pounds on Earth and one gee it would have to stay at one gee

it takes a mass of ~31250 slugs to weigh 1,000,000 lbs on the Earth, And 1,000,000 lbf to accelerate it at 1g
 
Ok that's great. It's a idea I have for a electric drive. If it works 1 gee travel will be the road to the stars. Best part is most of the things have been made for other things.
 
What will you use for fuel? It's a loooooooooong way to those stars.
 
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  • #10
Well if you can't get up to the speed of light you can never try and go faster then it?
 
  • #11
fuel around sol H2 and O the stars well nuclear
 
  • #12
It's very difficult to understand you when you type in sentence fragments and use no punctuation.
 
  • #13
One other point it is not a rocket there is no exhaust as long as there is power you have fuel. so neer by stars are years away
 
  • #14
marmstrong941 said:
One other point it is not a rocket there is no exhaust as long as there is power you have fuel.
You need fuel to provide power, not the other way around.
 
  • #15
Sorry better at making things in my mind and hands then putting them into words. My math is so so as well it does not make me wrong or a fool.
 
  • #16
No, I'm just trying to help.
 
  • #17
H2 and O are the fuel and with no exhaust it just has to coll down to water and be split bac to H2 and O
 
  • #18
Ok the main drive part has been made and as funny it may soundit will need a boiler.
 
  • #19
marmstrong941 said:
H2 and O are the fuel and with no exhaust it just has to coll down to water and be split bac to H2 and O
Generally, it's the exhaust that provides the propulsion. Conservation of momentum. The change in mass*velocity of the rocket ship in a forward direction equals the mass*velocity of the stuff you throw out the back.

Doesn't mean that electric power isn't feasible. You can already use electricity to power an electromagnetic accelerator that sends charged particles out the back incredibly fast (30 km/sec, for example). That means you don't have to throw nearly as much stuff out the back as with conventional thrusters, but you still have to throw stuff out the back. Plus, the further away you get from the Sun, the less electrical power will be available (due to that annoying inverse square law).
 
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  • #20
Ok this drive will not push it like a rocket it pulls it. There is no exhaust it is big and will need a big power supply 2 to 3 time the mass you want to move 5 to 10 times if you want to lift off of earth. Thats in watts The drive will shake a lot so the mass is at the back and the output is about 1/2 of 906480.59046179 joules or 668585.77257981
foot-pounds for one unit
 
  • #21
marmstrong941 said:
Ok the main drive part has been made and as funny it may sound it will need a boiler.
Why does it need a boiler?
[tag removed. It was only an experiment to see how tagging works]
 
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  • #22
marmstrong941 said:
H2 and O are the fuel and with no exhaust it just has to coll down to water and be split bac to H2 and O

If there's no exhaust, how does it provide thrust in order to accelerate?
 
  • #23
Drakkith said:
If there's no exhaust, how does it provide thrust in order to accelerate?
It's the vacuum, man.
 
  • #24
SteamKing said:
It's the vacuum, man.

Do you know which brand of vacuum by chance? Hoover? Dyson?
 
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  • #25
This thread should be closed

there's no supporting physics ...
its not even good sci fi ... there's more holes in this than in a block of Swiss cheeseDave
 
  • #26
The holes in Swiss cheese are a probabilistic phenomena.
Maybe this should be in quantum physics.
 
  • #27
davenn said:
This thread should be closed

there's no supporting physics ...
its not even good sci fi ... there's more holes in this than in a block of Swiss cheese

Indeed. Thread locked.

Marmstrong, you can contact me with more details if your wish and I will consider reopening the thread if your idea turns out to somehow fall within mainstream science.
 

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