Assumptions about supporting a system of fueling a machine.

[Link_Eternal]

This question has come up many time for me while discussing fictional machines, or systems that cannot be clearly measured like a lever or a pully.

Lets say you are supporting a system that maintains a state of being, lets take it slow and simple and say keeping a boulder 5 feet off the ground. On Earth just to be clear.

I'll keep this explicit:

The Rock - We'll use the 27 ft^3 4320 lbs boulder

In metric -

Mass: 1959.519kg

g: 9.8 m/s2

F=mg

Force needed to support The Rock barring external factors = 19203.2862 kg*m/s2 or N

You are given no facts revealing the efficiency of the system in place. Without you the system will fail, and the boulder will drop.

How much power/energy do you need to keep it up?

I believe this site seeks to keep any assumptions to a minimum, understandably so in fact.

With that said, do you assume the system was created by someone who:

Knows what they are doing, thus requiring less energy than if you did it yourself (Lets say half as much),

Does not know what they're doing, thus requiring the same amount of energy than if you did it, or

Is a complete incompetent, thus somehow requiring more energy than if you held it (Lets say twice as much.

The way I'm leaning, the only concrete fact we possess are the consequences of the system failing, which means the the amount of energy we must assume is needed would be equal to the consquences of not having it.

Obviously, context is important, but the point is you have none.

 

[Link_Eternal]

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[Matthew_Schroeder]

It's a case-by-case scenario, depending heavily on the mechanisms of the system. Even a simple seesaw mechanism can allow a human to lift far more than they would normally be capable of, and that is due to simple physics and not because the seesaw provides the energy to do so.

You could also take a single cog from a large machine and the whole system would fall apart, but that wouldn't mean that the single cog would "scale" to the output of the entire system.

 

[Link_Eternal]

That is a given, but the enitre point of this senario is that we have 0 details about the mechanics of the systemm so my question remains.

That is a good point, because systems in general rely multiple moving parts, so if one is missing the system fails. However, to relate to your real world connection. If you are using a pully system to keep this rock in the air, whatever rope you are using would be part of the system, but it is also bearing the full weight of the burden and would scale to the output, no?

 

[Matthew_Schroeder]

Pulleys make it considerable easier for a rope to lift something off the ground than it normally would, though.

 

[Link_Eternal]

No, it makes it considerably easier for the person pulling the rope to lift things off the ground. At the end of such a system, there is nothing between the last pully and the object being lifted, meaning, so long as the rope is secure, it is bearing the full weight of that 2 ton rock it could be that there is more than one rope, but that is systems mechanics information we are not given.

In a fictional scenario, you could be the rope in question, and have no info on how many pulleys are supporting you.

Also, in all those outlandish mecha storys (looking at you Gurren Lagann) - that I haven't even touched, btw - I highly doubt they explain how those machines function and, though I also doubt they tell us what powers them, wouldn't whatever powers them scale to the feats of the mechs?

 

[AstralKing7]

Spiral Energy poweres them ƒñÀÔÇìÔÖé´©Å lol I think

 

[Matthew_Schroeder]

Gurren Lagann is powered through what is basically an infinite, magical energy source, so I'm not sure why that is a used comparison.

And no, the rope in a pulley system wouldn't directly to the weight it is lifting because of the existence of the pulleys facilitating the process. The more complex and subdivided a system is, the less likely it is to directly scale to whatever is fueling it.

In regards to a Mech, though, it probably use but that is a very direct system.

 

[Link_Eternal]

Gurren Lagann was pointed at because it was outlandish, sorry.

For the rope, it depends on the type of pulley system you are using, as well ashow many pulleys you need. At its most basic, a pulley system just lets you exert your energy in a more conveinient direction, not changing the weight you have to pull, with a second pully the load on you is divided in two and the rope as well. When you have more pulleys it gets easier and easier, but again, depending on your set up, the weight being supported, by the rope itself can be the same force you are required to apply, or it could be the same weight as the object you are lifting.

Btw, using a see-saw analogy, the axel holding up the bars must still be capable of supporting the mass of everything on it.

 

[Link_Eternal]

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[Link_Eternal]

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