How hard would a power system like this scale?

[SpiraSpira]

Usain Bolt, the fastes human on the planet, runs at 44,72 km/hr. I'm guessing He'd be a 3-point-something based on your numbers. A 12 would mean: (Speed of sound: 1200 km/hr) 44x512= 22.500 km/hr. 22.500/1200 = Mach 18.
Hafthor Bjornsson, the strongest man, managed to deadlift 501 kilograms in 2020, breaking a world record. A 12 would mean lifting tonnes with no effort whatsoever. Perhaps even preventing jets from moving at full throttle for a light warmup in the morning. 501x512= 256.512 KG of deadlift.
A punch is several times the kinetic force of what a human can deadlift. A kick usually ranges from 500kg to 2 tonnes of kinetic force per square centimeter, and it's scientifically proven that a kick delivers 4 times the kinetic force of a punch when the same individual does it. A person with 12 strength would atomize anything they punch, probably generating vacuums and if you go full science, a black hole on impact due to matter compression.
A sneeze would create violent winds that could pop the eardrums of everyone nearby, they would shit diamonds, and if you manage to cut their skin, they'd bleed out in an instant due to their internal pressure.

This isn't realistic because at high speeds the aerodynamics of drag becomes controlling. Usain Bolt isn't running in a vacuum and neither is your hypothetical 12 equivalent. Consider that a linear increase in power does not equate necessarily to a linear increase in performance.

Take for example some aircraft:
The F-5 is a small single seat fighter jet that has about 40 kilonewtons of thrust, it can easily achieve mach 1.5 or so at full thrust.

The SR-71 is a larger aircraft, true, but it needs over 300 kilonewons to achieve something like mach 3.2. The friction from the air is so much that the surface temperature of the SR-71's skin is over a thousand degrees celsius at such speeds. See how much more thrust it needs just to go a little faster?

This would be different if they were flying in vacuum, of course.

 

[Biggest-Kusa-Out-There]

This isn't realistic because at high speeds the aerodynamics of drag becomes controlling. Usain Bolt isn't running in a vacuum and neither is your hypothetical 12 equivalent. Consider that a linear increase in power does not equate necessarily to a linear increase in performance.

Take for example some aircraft:
The F-5 is a small single seat fighter jet that has about 40 kilonewtons of thrust, it can easily achieve mach 1.5 or so at full thrust.

The SR-71 is a larger aircraft, true, but it needs over 300 kilonewons to achieve something like mach 3.2. The friction from the air is so much that the surface temperature of the SR-71's skin is over a thousand degrees celsius at such speeds. See how much more thrust it needs just to go a little faster?

This would be different if they were flying in vacuum, of course.

?
Ok, and? Why do you think about drag and not the entirety of biomechanics required to make it possible first before aerodynamics have a chance at showing up?
Blood pressure. Heartbeat/minute. Level of blood oxigenation. Body temperature. Muscle size. Bone density. How much thermal energy they produce/withstand before spontaneous combustion. Can the nervous system keep up?
Can something be alive with that much strength?
Lmao, drag.

 

[SpiraSpira]

?
Ok, and? Why do you think about drag and not the entirety of biomechanics required to make it possible first before aerodynamics have a chance at showing up?
Blood pressure. Heartbeat/minute. Level of blood oxigenation. Body temperature. Muscle size. Bone density. How much thermal energy they produce/withstand before spontaneous combustion. Can the nervous system keep up?
Can something be alive with that much strength?
Lmao, drag.

Because it is a fundamental problem in physics and paying a little lip service to physics when describing supernatural phenomena in stories gives them a sense of verisimilitude even when dealing with ridiculous and superhuman abilities.

In other words, the supernatural composition of a superhuman's body is inside the fantasy framework of the story, so you don't really have to explain it away. But as things interact with the natural world you do. "Air" exists, and someone that is merely exponentially stronger/more agile than another person will not move at exponentially greater velocities in the atmosphere. Including limitations based on actual physics will place less burden on a reader's ability to suspend their disbelief and allow you to have even more fantastical powers and abilities. In my opinion.

But you do you, brother (or sister or whatever.)

 

[Biggest-Kusa-Out-There]

Because it is a fundamental problem in physics and paying a little lip service to physics when describing supernatural phenomena in stories gives them a sense of verisimilitude even when dealing with ridiculous and superhuman abilities.

In other words, the supernatural composition of a superhuman's body is inside the fantasy framework of the story, so you don't really have to explain it away. But as things interact with the natural world you do. "Air" exists, and someone that is merely exponentially stronger/more agile than another person will not move at exponentially greater velocities in the atmosphere. Including limitations based on actual physics will place less burden on a reader's ability to suspend their disbelief and allow you to have even more fantastical powers and abilities. In my opinion.

But you do you, brother (or sister or whatever.)

Sure, but you're focusing solely in a single thing that can also be explained away in simple terms.
If the narrator goes:
"Timmy 'Two-nuts' jumped and flew off. Linear momentum thermostasis aerodynamic drag machinegun tzar bomba. He arrived at his destination."
The reader will never actually engage with the physics of the story. They should only see the actions of the characters.
"Timmy 'two-nuts' jumped and flew off. A sonic boom followed and he disappeared into the horizon at nauseating speeds. Ten minutes later he arrived at his destination."
Stories are more often than not, not about the actual laws regulating a world but about the actions of characters. So speaking about characters and their possible actions has more contextual value to the thread than to integrate something that nobody actually understands: drag.
Adding drag to the equation turns the narration into passive voice, which is not really fun.

Why does weight and mass matter? To showcase it.
"Timmy lifted the US Enterprise and threw it at the Kaiju."
Why do actual laws not matter as much?
"Timmy exerted a billion newtons of force to lift 90 metric tonnes of mass, then with the aid of [insert the appropriate term] he threw it at the kaiju at mach 18"

The specifics do not matter when storytelling in fantasy. Mentioning drag and air resistance clutters the story with numbers and concepts the reader probably has no solid knowledge on... which halts suspension of disbelief instead of aiding it because it's too real for fantasy. Characters may talk about it and question some things, but narration should not go there. That's not what the story is about.

 

[SpiraSpira]

Sure, but you're focusing solely in a single thing that can also be explained away in simple terms.
If the narrator goes:
"Timmy 'Two-nuts' jumped and flew off. Linear momentum thermostasis aerodynamic drag machinegun tzar bomba. He arrived at his destination."
The reader will never actually engage with the physics of the story. They should only see the actions of the characters.
"Timmy 'two-nuts' jumped and flew off. A sonic boom followed and he disappeared into the horizon at nauseating speeds. Ten minutes later he arrived at his destination."
Stories are more often than not, not about the actual laws regulating a world but about the actions of characters. So speaking about characters and their possible actions has more contextual value to the thread than to integrate something that nobody actually understands: drag.
Adding drag to the equation turns the narration into passive voice, which is not really fun.

Why does weight and mass matter? To showcase it.
"Timmy lifted the US Enterprise and threw it at the Kaiju."
Why do actual laws not matter as much?
"Timmy exerted a billion newtons of force to lift 90 metric tonnes of mass, then with the aid of [insert the appropriate term] he threw it at the kaiju at mach 18"

The specifics do not matter when storytelling in fantasy. Mentioning drag and air resistance clutters the story with numbers and concepts the reader probably has no solid knowledge on... which halts suspension of disbelief instead of aiding it because it's too real for fantasy. Characters may talk about it and question some things, but narration should not go there. That's not what the story is about.

You're quite right, except in the genre where specific numbers are used like the OP is discussing. For example, it is never really stated how much stronger Superman is in canon, so we can't even really get into whether or not his strength as exerted on the natural world is realistic. Honestly that is the best way to keep it in most situations.

However, when you're dealing with stratified power systems like the OP is describing where it is spelled out this dude is X times as agile as an average human that becomes a constraint and describing things wildly outside this constraint will generate cognitive dissonance in any readers who recognize it. Which is why I don't recommend things like this, even if you're going to do LitRPG and have out and out stat numbers you should leave some "slop" in what the numbers represent. Maybe for yourself as the author's notes you consider that each number is stronger by X much, I highly recommend not spelling it out in such white and black ways to the reader.

That said it is still a good idea to keep an eye to the constraints that physics (especially if it is physics that you have made up for your story) gives your characters because those are constraints that can be removed, so long as if they're properly explained why. For example, if two people are the same strength/agility you could explain that one is faster because of his affinity for "wind" or whatever reducing the drag that he experiences and allowing the wind to in fact help him when he runs, etc.

 

[Biggest-Kusa-Out-There]

You're quite right, except in the genre where specific numbers are used like the OP is discussing. For example, it is never really stated how much stronger Superman is in canon, so we can't even really get into whether or not his strength as exerted on the natural world is realistic. Honestly that is the best way to keep it in most situations.

However, when you're dealing with stratified power systems like the OP is describing where it is spelled out this dude is X times as agile as an average human that becomes a constraint and describing things wildly outside this constraint will generate cognitive dissonance in any readers who recognize it. Which is why I don't recommend things like this, even if you're going to do LitRPG and have out and out stat numbers you should leave some "slop" in what the numbers represent. Maybe for yourself as the author's notes you consider that each number is stronger by X much, I highly recommend not spelling it out in such white and black ways to the reader.

That said it is still a good idea to keep an eye to the constraints that physics (especially if it is physics that you have made up for your story) gives your characters because those are constraints that can be removed, so long as if they're properly explained why. For example, if two people are the same strength/agility you could explain that one is faster because of his affinity for "wind" or whatever reducing the drag that he experiences and allowing the wind to in fact help him when he runs, etc.

You're right... but there's the detail that the characters within the story treat the world and its 'fantastical laws' as their very reality instead of something to compare to our normality.
It would feel off for the narrator (in case of 3rd person semi-omniscient) to explain things for the reader's sake instead of the characters in-world. That fourth wall could be broken if the character is writing the story themselves, as the 'wall' is allowed to be commentated on to a certain extent.
People breaking these laws would not be actually breaking them, because going beyond our normality is their everyday reality.
This way, explanations regarding the behind-the-action reality are not precisely needed as you'd describe.
Immersion should not be broken for the purpose of making simple explanations to the reader. And yes, exposition and info-dump can be organic to the story through dialogue and events. That'd take time and abundant interaction to successfully solve the cognitive dissonance (which is valid when taking immersion into account).