How can a Coinshot / Mistborn "fly" using just a coin?

[+robardin]

As I recall it, Steelpushing is based on a line of force from one's center of gravity to a piece of metal - visible to the Allomancer as a blue line, whose thickness/strength was relative to the mass of the metal object in question, and distance from it. You could push with varying degrees of power on the object, but the force would always be along in that straight line. When Vin first tries it, she shoots straight up, and manages to balance at the apex. When Kelsier joins her, he explains that the body's sense of balance (that lets you just stand on one leg for a while, for example) translates to Steelpushing, so balancing on a Steelpush isn't that hard, but "move too much to one side, and you'd tip over like a weight on the top of a very tall pole".

I get that later she finds embedded parallel sets of iron bars in a kind of path going between cities, that Coinshots and Mistborn can use to "fly", using the pairs as "course corrections". And that Wax, living in a more modern age than the Final Empire, with steel structures and lampposts all around, could REALLY get around the city (and that a Lurcher could probably do about as well as Spider-Man in flinging himself around town).

What always struck me as dubious though was the way Elend, Vin, Zane, Wax, etc., can just drop a small coin - a clip - and launch off into the air. Unless they dropped it directly between their feet and stood very still, wouldn't the effect be just to shoot the coin away? Like if I were to jab my finger at an angle on a coin on my desk. Some or most of the force would be transferred directly into the desk (downward), depending on the angle, but some horizontal force would remain to shoot the coin away from me.

And if they did manage to drop it straight down, wouldn't they just shoot straight up, like Vin did in her initial exercise? Yet we often see someone drop a coin and flying up to land on a rooftop, go over a wall, etc., which seems to require some horizontal movement to do, otherwise instead of dropping down onto the roof or on the other side of the wall, you'd just come down exactly where you started from.

I didn't let this detract from my enjoyment of the Mistborn books by any means, but it's one of those details that has always been niggling me, and if someone could explain it away for me, I'd like it that much better

For example, in a city or somewhere with a lot of metal attached to structures nearby, you could always "push off" a bit on SOMETHING near you... Like door hinges or whatnot. Is that always the unspoken assumption?

 

Edited December 21, 2016 by robardin

[A Budgie]

Well, personally I've always thought that this works because of the streets of the city. Now, you tried this on your desk, but your desk is made of smooth wood, so the coin just slid. However, the streets would be different- personally, I've always imagined them made of cobblestones. Any coin would catch on the sides of the cobbles, and the sides of the stone would allow you to fly off. If done on dirt, since the weight of an entire body is being compressed into the tiny amount of area that is a clip, the coin would sink into the ground slightly.
All this should (plus the added fact some Mistborn/Coinshots do use things such as signs and doorhandles, or a coin plus extra bits of metal) be able to support you enough that you can actually fly.
I'm not sure if this is the 'agreed upon' definition, this is just what I think.

[aeromancer]

Yeah, I'd pretty much agree with that. The coin can just be used to go up, and then a slight push on anything nearby can be used to give the Mistborn additional push in other directions. And since when you have multiple vectors they all add up to a single vector, it gives the appearance as the coin just lifting you in a non-vertical angle.

[djammmer]

just like Spiderman... Except upside down. Spiderman doesn't fly... He cruises through the city with upside down arches (I.e. Pendulum swings), and when he gets to the peak of a swing he re-anchors a new pendulum... Using forward momentum, inertia while transitioning.

 

aren't flying mistborns the same thing, just upside down?

[The One Who Connects]

6 hours ago, djammmer said:

just like Spiderman... Except upside down. Spiderman doesn't fly... He cruises through the city with upside down arches (I.e. Pendulum swings), and when he gets to the peak of a swing he re-anchors a new pendulum... Using forward momentum, inertia while transitioning.

 

aren't flying Mistborn the same thing, just upside down?

I like this example, since it has similarities to what happens. Granted, I disagree with the upside down concept for Ironpulling at least.

Ironpulling is the same as what I understand Spiderman to do with his webbing, just without a visual rope for the pendulum model.

[+robardin]

On 12/25/2016 at 1:01 PM, djammmer said:

just like Spiderman... Except upside down. Spiderman doesn't fly... He cruises through the city with upside down arches (I.e. Pendulum swings), and when he gets to the peak of a swing he re-anchors a new pendulum... Using forward momentum, inertia while transitioning.

aren't flying mistborns the same thing, just upside down?

Yes, I've always pictured Lurchers being able to do the Spidey-thing in a modern steel skyscraper filled downtown type area (which Era 2 Mistborn is well on its way to becoming). But that requires the anchor point to be fixed - either far heavier than you are, or bolted in place somehow. Which is what I'm commenting on, how often Coinshots can fly off after dropping a small coin, versus making use of heavy ingots shallowly buried in the ground like the "steel highway" between cities in the Final Empire specifically to facilitate Coinshot/Mistborn flight without being obvious (the way an array of overhead metal frames in the middle of nowhere would be, to faciliate Spider-lurching between cities). Any angle to the coin relative to the person's CoG should result in the coin being shot away, instead of propelling the Coinshot.

The only reasonable answer is they're practiced enough to drop it between their feet for "pure" upward propulsion, and are usually implicitly using some other fixed or heavier anchor point nearby behind them to push themselves forward (in one scene, I think that turned out to be some unfortunate guards with steel breastplates, who were indeed pushed over a wall while Vin shot up and away, somewhat regretfully). After a while you just assume it.

I remembered one of the scenes that bothered me this way the most - the beginning of The Hero of Ages, when Elend arrives at Fatren's city to save it from a koloss attack - the skaa on the wooden gates and ramparts see him arriving on horseback, riding up the gates, dropping a coin, then springing "straight upward" to crest the gate and land on the rampart. Which would require some forward momentum as well as going "straight upward". In the case of a full Mistborn, of course, he could be silently Pulling as well on some metal inside the city once he reached or neared his apex or iron bolts in the gate (even if the gate had no metal bars, it probably wasn't pegged together with wood), so I'll have to find some example of "Wax in the Roughs" as a more squidgy example of "exactly how would a Coinshot manage to propel himself instead of the coin in this situation", though he also has that weight-storing Feruchemical ability that could also be a cheat (imagine if he momentarily made himself literally as light as a feather).

 

 

Edited December 27, 2016 by robardin

[GeneralStu]

Unless they are pushing off the coin at an extreme angle I'd say that the increase in friction due to the applied downwards force would be sufficient to hold the coin in place unless it was on a very smooth surface with little friction like ice. 

The friction force is proportional to the normal force on the object. Thus when they push downwards on the coin the force of friction is increased substantially. 

The downwards force necessary to lift off the ground has to be greater than the persons weight, therefore the normal force is increased by at least the amount the person weighs and most likely more. Since a normal coin probably weighs about 1/1000 of a persons weight this means the force of friction on the coin will increase around 1000 times. Easily enough to hold the coin in place. 

[+robardin]

45 minutes ago, GeneralStu said:

Unless they are pushing off the coin at an extreme angle I'd say that the increase in friction due to the applied downwards force would be sufficient to hold the coin in place unless it was on a very smooth surface with little friction like ice. 

The friction force is proportional to the normal force on the object. Thus when they push downwards on the coin the force of friction is increased substantially.

 

I guess this is true. I was doing tests using a coin and my finger on a desktop surface that is fairly hard and smooth, but a coin in dirt or against rough pavement would behave very differently, as would the force resulting not from a finger's push but an Allomantic one that was counterweighted by my entire body's mass.

 

[+robardin]

That now make me think an interesting "prank" to pull on a Coinshot would be to slick an area commonly used for dropping coins, kind of like strewing banana peels around the corner of a corridor, or on a dark stairway landing. Or finding out a common landmark - like a large bronze statue of the Survivor - was a standard Coinshot anchor, and unscrewing it from its base or something. Ha ha!

 

[djammmer]

I always imagined that they weren't just gently dropping the coins.... But using pushes to shoot the coins into the ground... So it's not just friction keeping them from moving.

[Jondesu]

13 hours ago, djammmer said:

I always imagined that they weren't just gently dropping the coins.... But using pushes to shoot the coins into the ground... So it's not just friction keeping them from moving.

Sometimes, but it does often say that they dropped a coin, then pushed on it. I don't think the effect would be that much different, though.