Lashing VS. Steel

[Sallin Zeras he/him]

What would be stronger? A coin infused ten times and launched forward with a basic lashing, or a steel push with duralumin on the same coin?

[Jondesu he/him]

4 hours ago, Orderbound said:

Well by the very properties of Lashing, I would have to say that it would win out. I think that in any situation, 10x gravity is far more powerful than a duralumin Push. I mean, falling off a building doesn't take that long, how about speed it up by ten times! Conversely, trying to catapult a coin up a building is going to take far longer.

Considering a normal push off a coin is enough to launch an Allomancer into the air, though, the force of the push must exceed the pull of gravity.  With Duralumin behind it, I would expect that could exceed 10x the force of gravity.  I think the trick would come down to how long each form of acceleration lasts: if the Stormlight keeps it accelerating for longer (which I think our examples in book show it probably would), it might not start as quickly, but it might travel further (or if they're opposing forces, it might be pushed back by the Duralumin push at first, but then once that's over, start moving back in the other direction).

[Elenion he/him]

19 hours ago, Jondesu said:

Considering a normal push off a coin is enough to launch an Allomancer into the air, though, the force of the push must exceed the pull of gravity.  With Duralumin behind it, I would expect that could exceed 10x the force of gravity.  I think the trick would come down to how long each form of acceleration lasts: if the Stormlight keeps it accelerating for longer (which I think our examples in book show it probably would), it might not start as quickly, but it might travel further (or if they're opposing forces, it might be pushed back by the Duralumin push at first, but then once that's over, start moving back in the other direction).

On 12/7/2016 at 5:09 PM, Orderbound said:

Well by the very properties of Lashing, I would have to say that it would win out. I think that in any situation, 10x gravity is far more powerful than a duralumin Push. I mean, falling off a building doesn't take that long, how about speed it up by ten times! Conversely, trying to catapult a coin up a building is going to take far longer.

Two contradictory theories, both referencing acceleration and time? Time to bring in the physics calculations!

 

If you Lashed an object 10 times, you would send it off at an acceleration of 10 times the force of gravity, or 98.1 meters per second squared. Translating this into force by using F=MxA and the mass of a US nickel (a perfect nickel is 0.005 kg), you get an applied force of only 0.4905 Newtons, which is about the same force as a roll of 10 nickels would exert on a table that they were sitting on. That's pretty sad, people.  However, if this acceleration is regardless of weight, if you lashed a 2000 kg car at the same velocity, you would rack up a whopping 196,200 Newtons of force! But sadly, for normal coin sizes, the force of 10 Lashings is actually really small.

 

50 minutes ago, Eki said:

The impulse might be what you want to consider, in the end.

Thanks for the idea! I'll look into that . . .

 

Setting Lashings aside for a moment, let's consider the Duralumin Steelpush. We don't have any data on how much force or velocity is involved in one of these, BUT some quick googling tells me that even the bulkiest human bone (the femur) can only withstand 5,000 Newtons of vertical force. Since the effect of a Duralumin-ed metal appears to depend only on how much metal the allomancer has available, I'll consider the allomancer's body strength as our limiting factor in this push. Assuming our allomancer is burning pewter to bring his other bones up to the same standard as his Femur, that the allomancer has themself securely anchored by a non-allomantic means, and that the push takes place over a quarter-second while the Allomancer's reserves are depleted, this means that the Allomancer can exert on him/herself a maximum of 1,250 Newton-seconds of impulse before he crushes himself.

 

Combining our two numbers, then, we learn that a Duralumin Steelpush has a limit of about 1,250 N-s on a coin before the allomancer crushes him/herself due to the reactionary force on him/her. To equal this impulse, the 0.4905 N of our ten lashings would have to be acting on the object for just over 2,500 seconds, or about 42 minutes, so unless our Radiant really overdid him/herself on the Stormlight breathing, than an impulse like that just would not be feasible.

 

TL;DR: Unless your Radiant has more than 42 minutes of Stormlight in him/her, then the allomancer conveys much more impulse both immediately and over time.

[Jedal he/him]

Well by the very properties of Lashing, I would have to say that it would win out. I think that in any situation, 10x gravity is far more powerful than a duralumin Push. I mean, falling off a building doesn't take that long, how about speed it up by ten times! Conversely, trying to catapult a coin up a building is going to take far longer.

[Eki]

It would completely depend on what was Pushed or Lashed. Lashing affects the acceleration (distance /  (time²)) of an object, while Pushing provides a force (mass * acceleration).

We don't know exactly how Lashing works, and how it affects more massive objects (after all, you can't Lash the whole planet or anything). But from what we know, you would get twice as much force on a coin if it's twice as heavy, because the acceleration is the same, but the mass is doubled. That would not be true for Pushing - a heavier coin would accelerate less. Though, if there is some kind of mass point where the two meet, I'm not sure where it is. It might be way out of the range for normal-sized coins.

But @Jondesu has a big point that it also depends on how long the two last. The impulse might be what you want to consider, in the end. Duralumin provides a short force spike, while Lashing acts over a longer time.

[Sallin Zeras he/him]

Ok, thanks, had that doubt since a long time 

[Eki]

Nice physicsing, @Elenion! However, while it doesn't affect your conclusion, Roshar has lower gravity than Earth, so the numbers are slightly off. I think a Rosharan g would be around 6 or 7 m/s², maybe.

Edit: Also, I just remembered, half a Lashing seems to cancel out gravity and make you weightless, right? That would mean that one Lashing is twice the Rosharan g... But on the other hand, there's no mention of counteracting the normal gravity when Lashing sideways. So it is a bit unclear exactly how Lashing works.

Edited December 9, 2016 by Eki

[Elenion he/him]

10 hours ago, Eki said:

Edit: Also, I just remembered, half a Lashing seems to cancel out gravity and make you weightless, right? That would mean that one Lashing is twice the Rosharan g... But on the other hand, there's no mention of counteracting the normal gravity when Lashing sideways. So it is a bit unclear exactly how Lashing works.

I've had that same thought about sideways lashings, and I eventually came to the conclusion that a Lashing takes a "fraction" of gravity and "flips" it into a new direction. Lash half of gravity up, and you have half up and half down, so no motion. Lash fully to the right, and you have all of your acceleration to the right and none downwards. But that's just my theory.

10 hours ago, Eki said:

Nice physicsing, @Elenion! However, while it doesn't affect your conclusion, Roshar has lower gravity than Earth, so the numbers are slightly off. I think a Rosharan g would be around 6 or 7 m/s², maybe.

I guess it depends on whether a Lashing is based on a set quantity of acceleration or relative to the gravity that the Lashing is made on. In other words, would a Lashing done on Scadrial (about the same gravity as us) flip gravity fully, or would it take a Lashing and a half to accomplish that result?

[Eki]

1 minute ago, Elenion said:

I've had that same thought about sideways lashings, and I eventually came to the conclusion that a Lashing takes a "fraction" of gravity and "flips" it into a new direction. Lash half of gravity up, and you have half up and half down, so no motion. Lash fully to the right, and you have all of your acceleration to the right and none downwards. But that's just my theory.

Yeah, but then, would multiple Lashings be possible? There would be no gravity left to take a fraction from. It might be useful just as a way to think about it, though. Even if it isn't how it really works.

2 minutes ago, Elenion said:

I guess it depends on whether a Lashing is based on a set quantity of acceleration or relative to the gravity that the Lashing is made on. In other words, would a Lashing done on Scadrial (about the same gravity as us) flip gravity fully, or would it take a Lashing and a half to accomplish that result?

My guess is that Lashings are just a comfortable unit for both the reader (IRL) and the Surgebinder (in-universe) to work with. So a Surgebinder who went to Scadrial (and could use their power there) would probably start off using Rosharan Lashings, but would adjust to Scadrial's gravity over time, and then that would be a more natural unit to work with for them. In other words, there's nothing special about a unit of Lashing except that it is much more intuitive for both the user and the reader. I don't really have any evidence for that though. I can think of a few reasons why it might be wrong, even...

Regardless, Lashing has only been shown on Roshar, so we have to assume that normally, Lashings are meant in relation to the gravity at that planet. (Which of course isn't the same value everywhere, but pretty constant.)

[Spoolofwhool]

My understanding is that the basic and reverse lashings change an object's spiritual connection to the planet, and through that, affect how it perceives gravity, as dictated by fundamental laws of the surge of gravity. A basic lash reinterprets the source(s) of gravitational force on an object to be in a new direction, usually. Reverse lashings work the same way, in that they cause objects in the area to behave as if the infused object is its gravitational source instead of the planet. I'm not sure exactly how to explain weightless half-lashings, but I'm guessing it has to due with creating a weaker connection to the planet while creating an equivalently weak connection upwards, while lashings in a perpendicular direction to up-down simply suppress the planetary connection as well. 

[The One Who Connects he/him]

10 hours ago, FiveLate said:

In both cases, wouldn't you reach a maximum velocity due to air resistance?

By technicality, yes and no.

Yes: They are both limited in maximum velocity by air resistance. Same as speed compounding and everything else so far.

No: If they don't have enough power/open space to reach terminal velocity, then one would be objectively better.

[Jondesu he/him]

11 hours ago, FiveLate said:

In both cases, wouldn't you reach a maximum velocity do to air resistance?

Unless the magic system enables you to push past that boundary.  In which case they'd begin to be ripped apart by the air resistance. 

[Yata he/him]

14 hours ago, Jondesu said:

Unless the magic system enables you to push past that boundary.  In which case they'd begin to be ripped apart by the air resistance. 

Just ask to your edgedancer/duskbringer friend to overcome this issues 

[SkyBolt]

Depends on how much steel the allomancer has in them, duralumin burns all the available metal, so the more you have, the stronger.