Combat and the physics of the Surge of Gravitation

[+Oltux72 he/him]

1 hour ago, therunner said:

True, unless they fire a lot of smaller objects, kinda like a shotgun.

That is exactly what they cannot do due to cube/squared issues.

[The Technovore he/him]

2 hours ago, Oltux72 said:

That is exactly what they cannot do due to cube/squared issues.

Forgive my stupidity but what exactly prevents a windrunner from gripping a fistfull of ball bearings, lashing them all at something to destroy, and then haphazardly flinging them in that direction? They're falling in the wrong direction, they'll be moving real fast, still carrying the momentum and force of 6 or more g's, and they'll spread. I don't---I'm not seeing the problem.

I mean look coinshots are cool because they can put a lot of sustained force behind their pushes, gravitation only uses g, but all you need to do is increase the mass and the difference is for most intents and purposes made up. You can't really dispute that a man will usually killed by a brick falling some 15ft, have that brick falling 100+ft at 6gs or more and a helmet isn't going to matter. Is it going to be as effective as a railgun or a cannon or even a high-powered rifle? No, but considering you're just a dude with stormlight it's a pretty good ability. Do we really have to throw math at each other to argue whether or not it is? Also consider that gravitation allows for a little more control than A-steel, as you can actually pick your direction, rather than just shoving outward from your center of gravity.

(Aiming with your torso has got to be annoying lol)

[+Oltux72 he/him]

1 hour ago, The Technovore said:

Forgive my stupidity but what exactly prevents a windrunner from gripping a fistfull of ball bearings, lashing them all at something to destroy, and then haphazardly flinging them in that direction? They're falling in the wrong direction, they'll be moving real fast, still carrying the momentum and force of 6 or more g's, and they'll spread. I don't---I'm not seeing the problem.

They want be moving really fast.

1 hour ago, The Technovore said:

I mean look coinshots are cool because they can put a lot of sustained force behind their pushes, gravitation only uses g, but all you need to do is increase the mass and the difference is for most intents and purposes made up. You can't really dispute that a man will usually killed by a brick falling some 15ft, have that brick falling 100+ft at 6gs or more and a helmet isn't going to matter. Is it going to be as effective as a railgun or a cannon or even a high-powered rifle? No, but considering you're just a dude with stormlight it's a pretty good ability. Do we really have to throw math at each other to argue whether or not it is? Also consider that gravitation allows for a little more control than A-steel, as you can actually pick your direction, rather than just shoving outward from your center of gravity.

The issue is that you are limited by mass. Do you want better armor and more Stormlight? Less ammo. A few coins won't matter. In fact the coins are your fuel, if it comes to that as a Coinshot or Mistborn. Not so for lashed weapons.

[ShardplateJoe III]

Hey y'all, your friendly neighborhood physics student here. I saw this discussion and found it interesting, so I created these graphics here that show us what the kinetic energy and momenta of several boulders on Roshar would look like (also calculated their terminal velocity on Roshar). Below are the momenta and kinetic energies of three hypothetical spherical granite boulders.

Spoiler

Kinetic energy is given in Joules.

Momentum is in units of kilograms meters per second.

The difference between the kinetic energy of an object and the momentum of an object is subtle, but energy is the ability to do work, while momentum is the mass of the object multiplied by the velocity of the object, while kinetic energy is one half of the mass multiplied by the velocity squared, which is why a bullet and a fast baseball may have the same momentum, but the bullet has much more kinetic energy, making getting hit by a bullet objectively worse.

One of the biggest trebuchets in the world could launch a 150 kg projectile at 70 meters per second (source). That is a kinetic energy of 3.67 * 10^5 Joules, with a momentum of 10^4 kg m/s. The smallest of our hypothetical boulders has 6.5 * 10^6 Joules at terminal velocity, while the biggest has 1.67 * 10^9 Joules. So, the smallest of our boulders has about 20 times the kinetic energy of one of the largest medieval siege engines in the world, while the biggest has four orders of magnitude more kinetic energy than the same siege engine, and this is using one lashing on unengineered boulders. 

It is not unreasonable to say that Windrunners and others who can use gravitation are among the most powerful siege engines ever seen, especially since you consider the fact that its not like there is a shortage of stone on Roshar, especially if you have access to either a shardblade or a soulcaster, which our characters have ample access to. 

Sorry for how big the graphics are, but here are some quick thoughts I had, and I better get back to my homework.

Edited March 24, 2021 by ShardplateJoe III
clarity

[The Technovore he/him]

@ShardplateJoe III Absolutely gorgeous, thank you

[therunner he/him]

@ShardplateJoe III Awesome graphics!

I would point out that while as siege engines Windrunners/Skybreakers are unparalled in cosmere as we know it, in person to person combat happening in ranges of ~50 meters max, lashed projectiles could not achieve their terminal velocities, unless lashed ~20 times or more, which would limit their effectiveness compared to coinshots.

But this nicely illustrates that despite their superficial similarity, steelpushing vs gravitation have different strengths and weaknesses.

[ShardplateJoe III]

 

17 hours ago, The Technovore said:

 Absolutely gorgeous, thank you

 

10 hours ago, therunner said:

Awesome graphics!

Thank you!

10 hours ago, therunner said:

I would point out that while as siege engines Windrunners/Skybreakers are unparalled in cosmere as we know it, in person to person combat happening in ranges of ~50 meters max, lashed projectiles could not achieve their terminal velocities, unless lashed ~20 times or more, which would limit their effectiveness compared to coinshots.

But this nicely illustrates that despite their superficial similarity, steelpushing vs gravitation have different strengths and weaknesses.

For sure, in fact there is an argument to be made that against another user of gravitation, lashed projectiles would be completely useless without extreme levels of tact, the reason being that they would now be accelerating at the same rate as your opponent (off the top of my head, we do see the Skybreakers practicing with lashed projectiles, but they do have to be clever about how they use them) so unless you lash the projectile several times over, and it is designed to minimize drag, you are almost never going to hit an opponent in a meaningful way with your projectiles. In fact, the more surface area an object has compared to its volume, the smaller its ability to accelerate due to gravity is, and the lower its terminal velocity, which is why you can drop a bug from a weather balloon and it will survive, but do the same with an elephant and things will get messy.

If I'm thinking about this correct, a Windrunner using two lashings to outrun a projectile thrown with two lashings will almost always outrun said projectile, unless the projectile was designed to minimize drag, due to the fact that the windrunner will have a greater mass to surface area ratio than the projectile was.

However, against ground troops, a gravitation user would be devastating.

 

Edit: I just thought of a a few uses where if a gravitation user was being pursued, they could lash a projectile backwards. That would be a good situational use of a projectile.

Edited March 25, 2021 by ShardplateJoe III

[TheOneEyedFox]

I think the best method for this would be for the runner in front to pull all projectiles of others to his arrow shot at the enemy.