Effects of Iron Feruchemy

[darniil]

Well, Wax did switch between tapping and filling pretty quickly while he was flying through the air, off of the balcony.

[ulyssessword]

Don't the cannonballs still weigh 30lbs or whatever, the entire time?

Yes, and they would drag him down quite a bit, but with skill and practice (and possibly allomantic pewter), it might be possible for a person to do.

I don't think this one works. If we assume physical strength is constant and velocity is conserved (as you do), he could simply jump while at low weight and be propelled high into the air. If we assume momentum is conserved and physical strength is proportional to mass (as I do), he could jump while tapping his ironminds, then immediately start filling ironminds, and fly off. Either way, he can fly without cannonballs.

Yes, that would be a much easier way of doing it, but what you are describing isn't flying, it's just jumping really high and fast. The cannonball method can be controlled into hovering, turning, going up, down, and to the sides by using small adjustments. This could be useful if you needed to jump around a corner or two without touching the ground, and it breaks physics more (which is what I was trying to show).

For a better (but less thematic) example for introducing momentum (#2), replace the traincar with a space shuttle or escape pod (lower mass, no friction), and it could theoretically reach relativistic speeds, eventually. This also works for flight (#3).

I'll try to break cannonball-flight (#3) down more, as I didn't describe it very clearly the first time. In hindsight, it might require a pewter/iron twinborn to work effectively.

Starting stats: feruchemist: normal 75 kg, cannonballs always 10 kg each.

Start with the cannonballs held high, at low mass.

1. With mass still low, and bring the cannonballs downward as quickly as possible. This will pull you upward at 4x the speed of the balls (discounting gravity) because you are lighter than the two cannonballs.

2. Increase mass to 300 kg, and stop the cannonballs as they pass your shoulders and reach waist level. This will cause you to lose ~1/15 of the speed of the cannonball, as you are much more massive than the cannonballs.

3. With your mass still high, pull the cannonballs upward. Again, this will slow you ~1/15 of their speed because you are much more massive than the cannonballs.

4. Decrease mass to 5 kg again as the cannonballs reach your shoulder level, heading up. Slowly extend your arms as they pull you upward to ~4/5 their speed (they are more massive than you).

5. repeat from step 1. To hover, use slightly less effort, to turn, add a slight curve to their path, to travel, don't be parallel to the ground.

I agree with darnill's observation about quickly changing between filling and tapping metalminds, it seems to be quite possible.

Edited September 18, 2011 by ulyssessword

[Asha'man Logain]

A few things. Force = Mass * Accerleration. Acceleration = change in Volocity. Volocity = Speed and direction. As for momentum, isn't that just another word for Inertia? If not what do we mean by it?

As for the thought problems, 1 and 2 would work fine, 3 not so much. No matter your mass the cannonballs stay the same, they will always be attracted to the ground at the same rate.

[ulyssessword]

A few things. Force = Mass * Accerleration. Acceleration = change in Volocity. Volocity = Speed and direction. As for momentum, isn't that just another word for Inertia? If not what do we mean by it?

As for the thought problems, 1 and 2 would work fine, 3 not so much. No matter your mass the cannonballs stay the same, they will always be attracted to the ground at the same rate.

Momentum = velocity * mass

Inertia = mass

#3 should work, even though nothing changes that the entire system is pulled to the ground at a rate of 9.81 m/s^2, it should be able to get enough acceleration to overcome it.

More numbers and calculations! I'll do a step by step breakdown of the entire process, (hopefully) showing that it could work.

1. With mass still low, and bring the cannonballs downward as quickly as possible. This will pull you upward at 4x the speed of the balls (discounting gravity) because you are lighter than the two cannonballs.

2. Increase mass to 300 kg, and stop the cannonballs as they pass your shoulders and reach waist level. This will cause you to lose ~1/15 of the speed of the cannonball, as you are much more massive than the cannonballs.

3. With your mass still high, pull the cannonballs upward. Again, this will slow you ~1/15 of their speed because you are much more massive than the cannonballs.

4. Decrease mass to 5 kg again as the cannonballs reach your shoulder level, heading up. Slowly extend your arms as they pull you upward to ~4/5 their speed (they are more massive than you).

5. repeat from step 1. To hover, use slightly less effort, to turn, add a slight curve to their path, to travel, don't be parallel to the ground.

Notes:

I pulled the numbers for the time it takes to bring the cannonballs out of thin air, but 1/3 of a second seems reasonable, if a bit strenuous. The velocities were derived based on an arm length of 1 m.

Changing from tapping and filling ironminds happens instantly between the steps where applicable.

The cannonballs' velocity is measured relative to your body, not the ground. Because of this, the gravity calculation for the body also applies to it.

The positive vector is up.

Gravity is 2% stronger (10.00 m/s^2 vs. 9.81 m/s^2) on Scadrial, because it is better for math.

EBV (ending body velocity) formula is gravity added to an expansion of conservation of momentum,

The momentum of the body and the momentum of the cannonballs at the start = The momentum of the body and the momentum of the cannonballs at the end.

Momentum is mass multiplied by velocity, so expanding that sentence, you get:

Body mass * starting body velocity + cannonball mass * starting cannonball velocity = Body mass * ending body velocity + cannonball mass * ending cannonball velocity

to abbreviate:

(BM * SBV) + (CM * SCV) = (BM * EBV) + (CM * ECV) => reorganize a bit...

BM * EBV = (BM * SBV) + (CM * SCV) - (CM * ECV) => divide both sides by the body mass...

EBV = ((BM * SBV) + (CM * SCV) - (CM * ECV)) / BM => simplify some...

EBV = (CM / BM) * (SCV - ECV) + SBV => and voila an easy to use formula for momentum transfer.

change in velocity due to gravity is simple, it is time * acceleration: (t * g)

Acceleration due to gravity (g): -10.00 m/s^2

Cannonballs mass (CM): 20 kg

Step 1: Above head to shoulder level

Body mass (BM): 5 kg

Starting Body Velocity (SBV): 0 m/s

Starting Cannonball Velocity (SCV): 0 m/s

Time elapsed (t): 0.33 sec

Ending Cannonball Velocity (ECV): -6 m/s

Ending Body Velocity: ???

Ending Body Velocity (EBV) = loss from gravity + change from cannonballs + starting velocity

EBV = (t * g) + ((CM / BM) * (SCV - ECV)) + SBV

EBV = (0.33s * -10.00 m/s^2) + ((20 kg / 5 kg) * (0 m/s - -6 m/s)) + 0 m/s

EBV = (-3.3 m/s) + (4 * 6 m/s) + 0 m/s

EBV = -3.3 m/s + 24 m/s + 0 m/s

EBV = 21.7 m/s

Step 2: Shoulder level to waist level

Body mass (BM): 300 kg

Starting Body Velocity (SBV): 21.7 m/s

Starting Cannonball Velocity (SCV): -6 m/s

Time elapsed (t): 0.33 sec

Ending Cannonball Velocity (ECV): 0 m/s

Ending Body Velocity: ???

Ending Body Velocity (EBV) = loss from gravity + change from cannonballs + starting velocity

EBV = (t * g) + ((CM / BM) * (SCV - ECV)) + SBV

EBV = (0.33s * -10.00 m/s^2) + ((20 kg / 300 kg) * (-6 m/s - 0 m/s)) + 21.7 m/s

EBV = (-3.3 m/s) + (1/15 * -6 m/s) + 21.7 m/s

EBV = -3.3 m/s - 0.4 m/s + 21.7 m/s

EBV = 18 m/s

Step 3: Waist level to shoulder level

Body mass (BM): 300 kg

Starting Body Velocity (SBV): 18 m/s

Starting Cannonball Velocity (SCV): 0 m/s

Time elapsed (t): 0.33 sec

Ending Cannonball Velocity (ECV): 6 m/s

Ending Body Velocity: ???

Ending Body Velocity (EBV) = loss from gravity + change from cannonballs + starting velocity

EBV = (t * g) + ((CM / BM) * (SCV - ECV)) + SBV

EBV = (0.33s * -10.00 m/s^2) + ((20 kg / 300 kg) * (0 m/s - 6 m/s)) + 18 m/s

EBV = (-3.3 m/s) + (1/15 * -6 m/s) + 18 m/s

EBV = -3.3 m/s - 0.4 m/s + 18 m/s

EBV = 13.3 m/s

Step 4: Shoulder level to above head

Body mass (BM): 5 kg

Starting Body Velocity (SBV): 0 m/s

Starting Cannonball Velocity (SCV): 6 m/s

Time elapsed (t): 0.33 sec

Ending Cannonball Velocity (ECV): 0 m/s

Ending Body Velocity: ???

Ending Body Velocity (EBV) = loss from gravity + change from cannonballs + starting velocity

EBV = (t * g) + ((CM / BM) * (SCV - ECV)) + SBV

EBV = (0.33s * -10.00 m/s^2) + ((20 kg / 5 kg) * (6 m/s - 0 m/s)) + 13.3 m/s

EBV = (-3.3 m/s) + (4 * 6 m/s) + 13.3 m/s

EBV = -3.3 m/s + 24 m/s + 13.3 m/s

EBV = 34 m/s

The cycle would then begin again, with each cycle of the four steps adding a total of 34 m/s to the feruchemist's upward velocity.

Edited September 19, 2011 by ulyssessword

[Musicspren]

I see two potential issues (although it may be that I just became lost in all the calculations). One, are you counting the difference between your acceleration of the cannonballs and that of gravity? Gravity doesn't just pull you down (which you have clearly accounted for), it also pulls the cannonballs down, so you have to push them down more quickly than gravity, and you are only going to gain velocity past that point. Perhaps you did that and I just couldn't tell in the calculations.

For the second issue, I will take as given that physical strength remains constant (I'm not convinced, but for the sake of this example, I won't argue about it). However, that means that lifting your arms when your total mass is 300kg will be difficult to do and, beyond that, do very quickly, because your arms will weigh several kilograms each (and you'll still be lifting the normal weight cannonballs).

The second issue can be circumvented with a pewter misting/iron ferring twinborn, and I'm not certain how much the first would affect the final result (or if it is even an issue; you may have addressed it and I just couldn't tell by your formulae).

Despite those potential issues, that was impressively well thought-out.

[ulyssessword]

I see two potential issues (although it may be that I just became lost in all the calculations). One, are you counting the difference between your acceleration of the cannonballs and that of gravity? Gravity doesn't just pull you down (which you have clearly accounted for), it also pulls the cannonballs down, so you have to push them down more quickly than gravity, and you are only going to gain velocity past that point. Perhaps you did that and I just couldn't tell in the calculations.

The cannonballs' velocity is measured relative to your body, so they should be affected by everything that affects the body, including gravity.

For the second issue, I will take as given that physical strength remains constant (I'm not convinced, but for the sake of this example, I won't argue about it). However, that means that lifting your arms when your total mass is 300kg will be difficult to do and, beyond that, do very quickly, because your arms will weigh several kilograms each (and you'll still be lifting the normal weight cannonballs).

Yeah, probably, I thought of that, but ignored it in favour of clarity. This example would probably require a pewterarm to do as described, both to get the speed at high mass, as well as possibly avoiding dislocating your shoulders in step 3 (due to decreased material strength). In hindsight, the example is more of a proof of concept than a description of what would actually happen. Edited September 19, 2011 by ulyssessword

[PeterAhlstrom]

Your ideas are intriguing to me and I wish to subscribe to your newsletter.

[ulyssessword]

I just realized that there is an alternative to our assumption that change in physical strength needs to be either directly proportional to mass or else nonexistent. A simple system where (for example) reducing your mass by 50% leads to losing 5% of your strength, and gaining an extra 100x mass leads to 10x extra strength would fit with all of the examples in this thread.

A ratio of 10x mass to 1x strength would work, along with anything in that range. This would still conserve energy (doesn't violate Feruchemical properties), make people slower when tapping iron and quicker while filling it (feel heavy/light, be lighter on their feet or weighted down), and still allow mobility at the ends of the spectrum (Wax lifting his arms at 100x mass, as well as being more responsive/lighter on his feet at 75%). It also avoids the direct contradictions that both sides could not adequately explain.

This brings my opinion to:

Mass/density (not weight/acceleration due to gravity)

In addition to full material strength, some physical strength, as well, but not all of it.

Velocity is conserved when changing mass while moving, not momentum.

My main contention with conserving momentum doesn't fit into arguments well: It requires a more intelligent system than Feruchemy for it to work as expected. It would need to:

1. Conserve velocity inside of the body (to avoid feruchemist explosions, blood flow etc...),

2. Conserve momentum outside of the body (by definition)

3. Shift its reference point intelligently (to avoid flying to the front/back of trains or off the planet)

Feruchemy is not that complex, I could accept it if it was Allomancy, but Feruchemy is simpler than that for every other metal. Even though velocity conservation breaks physics more, it is simpler.

Your ideas are intriguing to me and I wish to subscribe to your newsletter.

Edited September 25, 2011 by ulyssessword

[Musicspren]

(Sorry about the delay, semester is busy)

This brings my opinion to:

Mass/density (not weight/acceleration due to gravity)

In addition to full material strength, some physical strength, as well, but not all of it.

Velocity is conserved when changing mass while moving, not momentum.

I like this idea quite well as it could explain basically everything we've seen. The one thing I don't like is how the amount of physical strength gained lost is not proportional, and so feels a little arbitrary. However, this being Scadrial, it may be something simply like 1/4 (I try to assume things related to exponents of 2 on that world in particular), which would certainly make your arms feel heavier, but, with enough innate strength, could still allow you to lift them. You could still super-punch, which we haven't seen used to its full potential yet. I think your most recent version fits best of all of ours so far with the facts from the books.

Now we just have to wait for Alloy of Law to come out so we can change all our opinions.

Your ideas are intriguing to me and I wish to subscribe to your newsletter.

Here's your subscription, sir.

[ulyssessword]

I was thinking the ratio would be higher, either 8:1, or 16% (~6:1). 16:1 was my other guess, but that seems too high to allow Wax to have lifted his arms above his head at 100x mass. 4:1 or even 2:1 would work as well, we just don't have enough details yet.

Now we just have to wait for Alloy of Law to come out so we can change all our opinions.

Yup, funny the way that evidence does that.

[Wispsy]

Wait are you saying the feruchemist gains an acceleration of 21.7 meters a second by bringing a cannonball from above their head to their shoulder? Standing on the ground?

[Wispsy]

Also isn't this abit extreme just to fly when you can control weight? Just make a pair of strap on wings (whilst being really light) and fly just like a large bird if u can't do it with allomancy

Edited October 8, 2011 by Wispsy

[ulyssessword]

Wait are you saying the feruchemist gains an acceleration of 21.7 meters a second by bringing a cannonball from above their head to their shoulder? Standing on the ground?

The Feruchemist gains that velocity. As Musicspren pointed out, the example may require a pewter/iron twinborn to do as described, but it is physically sound.

Also isn't this abit extreme just to fly when you can control weight? Just make a pair of strap on wings (whilst being really light) and fly just like a large bird if u can't do it with allomancy

Yes, that would be much easier, but it would require you to have wings along. Also, the point of that example wasn't practicality, it was to illustrate what taking the system to its logical conclusions entails. Flying with wings is hardly novel, but when is the last time you heard of the ability of flight being gained by holding inert weights?

[darniil]

So, those who have finished Alloy of Law - shall we continue this thread? There was information in the book that directly pertains to this topic.

[Earendil]

My Crazy Idea for explaining Iron is as follows:

In Physics, there is a Gravitational Constant. It's the number that's used to calculate Gravity for the whole universe. It's something like 6.6*10^-11. What if, when Wax is "storing weight" he's reducing that number just slightly for all the particles connected to him so that the world doesn't pull on him as much. When he's "drawing out weight" he's increasing that number so that the world pulls on him a little more.

Initially, this is what I thought was happening as well (before I read Alloy of Law). However, Wax specifically states on several occasions that tapping/filling his metalmind would not change his trajectory during a jump (at one point, he makes himself heavy enough to blow out the ceiling while in mid-air, so we know that's not just his perception), so he can't be changing his personal gravitational constant--that would change the way he moves in the air.

It's equally interesting that his density doesn't change (at least noticably). Also, if it does change mass, it does it in a way that violates the law of conservation of momentum (normally, adding mass without adding energy would decrease speed). Regarding the question of strength, I see it in the same vein as the effects of a mistborn burning atium--there's a corresponding change to make you capable of utilizing the power.

[Kurkistan]

Regarding strength, we have another fairly ironclad example of some amount of normal strength being retained while Filling an Ironmind:

Page 169

Waxillium began a quick search of the house, and started refilling his metalminds as he did. He became much lighter, about half his normal weight. Any more than that and it became difficult to walk normally, even with clothing and guns weighing him down. He was practiced at it, though. [Emphasis added]

Wax's "moon-walking" problem could only happen if he retained at least a degree of his normal strength.

It also has just occurred to me that clothing/weapons would present a huge problem to someone filling an Ironmind if their strength was decreased as well, since he/she would have to move "heavy" materials along with their lighter body.

Edited November 10, 2011 by Kurkistan

[Satsuoni]

You know, I kind of have a theory that seems to fit both conservation of momentum and velocity. The idea is simple: assuming that Scadrial to some degree conforms to Einstein Theory of Relativity, we can say that mass m is a measure of energy content of the body. Then what the feruchemist is storing is actually his energy content, drawn proportionally from his potential, kinetic and mass energies. That would mean, since all these energy formulas contain mass in the same power, that his velocity, altitude, and the speed of light will stay the same, while his mass temporarily drops. Then, when he draws energy back, it also increases proportionally, so his velocity stays the same while momentum grows due to added energy. In this way, although he won't be able to make himself quite as massive while in motion, the difference will be proportional to v^2/c^2, that is, insignificant on the non-relativistic velocity levels. So, when he uses his abilities to power something, he loses some energy from metalmind, eventually (in a few millenia) running out.

So in the end, like this: you remove energy/mass from the world for a time, and then can add the same energy/mass for a time, resulting in conservation.

[Green Hoodie Mistborn]

I wonder, in all of this discussion, how does the truth that Feruchemy has diminishing returns affect any of this, if at all?

It requires greater than x4 stored mass/density/weight to become x4 as massive.

Would that affect any of this at all? As there seems to be a loss of energy going on there that could affect any conservation of energies?

[Kurkistan]

I wonder, in all of this discussion, how does the truth that Feruchemy has diminishing returns affect any of this, if at all?

It required greater than x4 stored mass/density/weight to become x4 as massive.

Would that affect any of this at all? As there seems to be a loss of energy going on there that could affect any conservation of energies?

You can easily get far more mechanical energy from iron Feruchemy than the "energy" you lose when you draw upon a large amount of weight. I know that other people have posited thought experiments, such as the "bowling ball flight" example, but the first thought experiment that occurred to me seems fairly intuitive and doesn't rely upon drawing any amount of weight from ironminds:

Setup:

A scale essentially the size of a seesaw attached to some means of transferring excess energy out of the system.

On one end of the scale is an iron Fering. On the other end is a weight which is approximately half as heavy as the unaltered Fering.

a) The Fering begins with their side of the scale at its minimum height and the weight's side at its maximum.

b.) The Fering then stores all of their weight in an ironmind, causing the weighted end of the scale to descend and the Fering to ascend.

c) The Fering then stops storing weight, causing the scale to return to the state it was in at step 'a.'

d) Rinse and repeat. Some energy loss due to friction and whatever mechanism we have gaining energy from the system, but you just got a Feruchemy-powered perpetual motion plus machine.

Edited November 18, 2011 by Kurkistan

[Thought]

It's equally interesting that his density doesn't change (at least noticably).

Why would we ever directly notice? Density is mass divided by volume, but skimming doesn't change volume. However, it is strongly implied that density does change. Remember in WoA when Sazed glides by filling an iron mind? His volume (and surface area, which is somewhat related) doesn't change, but suddenly he doesn't fall as fast. He is reducing his mass, which affects his density, and substantially lowers his terminal velocity.

Additionally, since it seems like the question of strength was never definitively answered, I thought I'd mention that storing strength must also store a little mass, thereby setting a precedent. Sazed's muscles shrink when he stores strength. If his mass remains the same, then his density must be increasing. But that must mean that mass is being transferred from one section of his body to another. An oddity, certainly, but the real conundrum comes when he taps strength. He can become quite huge, but if his mass doesn't change, then his density decreases substantially. This would in turn alter his terminal velocity, mimicking skim-gliding. Further, because he is less dense, he would also be injured more easily. None of this definitively says that when Sazed taps or stores strength that he is also affecting the related mass of his muscles and body, but it implies that he is.

[whynaut]

Tell me if this is silly, but perhaps storing weight actually stores the gravitational force pulling you toward the planet rather than storing something physical within the body. In this way storing weight could be similar to Lashing.

[Aradel]

Tell me if this is silly, but perhaps storing weight actually stores the gravitational force pulling you toward the planet rather than storing something physical within the body. In this way storing weight could be similar to Lashing.

Except that the person behaves like he's changed mass to other objects as well. If it was just storing gravity, Wax couldn't throw inertia around the way he did.

[vertigo 1]

what if you tapped weight when you jumped, then stored it mid-air?

[ThirdGen]

what if you tapped weight when you jumped, then stored it mid-air?

 

The opposite of this.

Edited January 14, 2015 by ThirdGen

[natc]

what if you tapped weight when you jumped, then stored it mid-air?

Well, your falling speed is still the same because gravity just works that way. Your horizontal velocity wouldn't really change either because you are not exerting force horizontally in midair. Air resistance shouldn't really change much.

Is it supposed to do anything? Physics is not my forte.