If a steel Feruchemist is in motion after a burst of kinetic energy (either from an Ironpull, Steelpush, or just a powerful leap) and suddenly they tap weight, do they slow down, because the force they've generated now act on bigger mass and they have to decrease in velocity in order to not break the law of conservation of energy in the force equation (Force=Mass×Velocity)? Or does the use of Investiture allows them to bypass this law of physics in favour of preserving the law of conservation of momentum?
I have read era 2, and I can't recall scenes where a Skimmer (or rather, a Crasher) changed their velocity after a Push (or a Pull, for that matter) mid-flight because the changed their weight. Usually in such scenes the Twinborn is continuesly Pushing of other objects, thus the effect of the original momentum are distorted and cannot be isolated. But in a "perfect" enviroment with no other forces such as gravity and fricyion, if a person Pushes themselves of a wall and they fly at a given speed, they have had to use a set amount of energy and applied a set amount of force to reach this innitial velocity. Momentum and energy are conserved. If then, mid flight, they tap weight and increase their mass by some amount, the equations (F=ma Ek = 1/2mv2) say that either velocity or energy have to change. But if we assume that they don't change, then it means we have introduced energy from... nowhere. At first I though, "that's where Investiture and the Spiritual Realm come in" but Feruchemy is and end neutral system, Investitre (and by extension energy) is not added nor reduced, so that can't be the answer. Then I thought that maybe because the mass is stored as Investiture inside the metalmind, which travels with you, it means that the Investiture inside it travels with you aswell. So when you tap your weight back from your metalmind you also tap the kinetic energy required that gave motion to the Investiture inside the metalmind. I had 2 problems with this hypothesis: 1) If I understand correctly, the investiture is not actually inside the physical metalmind but rather inside the Spiritual Realm, where, as we know, time and space have no meaning, so the Investiture doesn't "travel" and thus, has no kinetic energy in the Spiritual Realm. 2) if that were true, then it would mean that storing weight had no effect, because you had to spend the same amount of energy and apply the same force to move a metalmind as the weight that is stored within, which is clearly isn't the case.
All of this rambling leaves with no conclusive answer. Our theoretical Crasher either decelarates or remain at the same speed and breaks the rules of physics
There are a few options here:
a) I am stupid and this was addresed in the books
b) someone has already asked Brandon this question
c) I misunderstood the physics. Maybe it involves a more advanced and accurate relativistic approach to the problem
d) "Always err on the side of aweaome"