The Gun Devil is extremely large.[1] I want to know how heavy it is, and then get KE from that.
METHODICA[]
I'll be assuming the trees next to it here are Japanese cedar/Cryptomeria japonica trees because... Look at 'em. (Said trees) (are around) (20m) (tall.)
From that, I'll make some assumptions about its composition. It looks like a lot but I promise it's just explicitly stating things that normally go without saying.
- The upper torso is has the same density as the human body (slightly lower than water but that's for the whole body which has space like inside your torso, since it's just the head I'll use 1000kg/m3) for being made of human heads. It will be modelled as a triangular prism, cuz look at it. Giant chunky flesh 'n bone dorito.
- The neck will be modelled as a frustum with the base at his shoulders and the truncated top right where the head-gun starts.
- The arms are, for the most part, identical, i.e finding the mass of one will then just be multiplied by 2.
- The arms will be made of 6 guns each. 5 very clearly visible and then the shadow of one behind.
- Leaning on the CSM Wiki's page, the guns in question'll be an AK-47, 2 M16A1s, 2 M4 Carbines (these 2 guns seem to be repeated) and an Mk18 to make the 6.
- The guns are of a similar length.
- The 6 belts hanging from its waist-thing are roughly of equal length. They don't look to be any shorter than each other and I cannot be bothered to manually count the bullets in all 6. All bullets in the belt will be 7.62x51mm except clearly not 51mm.
- The head, on account of being the a good portion of a handgun, will be assumed to be 50% of the M1911's mass.
I'll be using the latter shot of it with its arms spread wide to get its proportions as it's in higher detail, and so should be more accurate.
MATHEMATICA[]
- Sugi tree - 266.58px | 20m
- One of GD's bullets - 38.05px | 2.855m
- GD's torso width - 81.79px | 6.136m
The Bullets[]
I count 57 bullets in a single belt.
- A real 7.62x51mm has an overall length of 71.1mm or 0.0711m.
- The bullets here are 2.855m long, scale factor is 40.15x.
- Assuming the regular one is a 147gr FMJ (see linked wikipedia page above), 147gr = 9.52543977g.
- Mass of one big bullet is 40.153 * 9.52543977 = 616,520g or 616.5kg.
- 6 belts * 57 bullets/belt...
210,850kg for the bullets alone.
The Torso[]
Cleaner pixel scaling. The lines are a little jank but it makes sense to do it that way since he's not perfectly head-on.
- One of GD's bullets - 85.09px | 2.855m
- GD's torso height - 422.50px | 14.17m
- GD's torso width - 327.39px | 10.98m
- Frontal area = 1/2 * 14.17 * 10.98 = 77.84m2
- Width was acquired in finding out the size of the bullet, so...
- 77.84 * 6.136 = 477.6m3.
- Multiply that by 1000kg/m3 (see assumptions at top), 477,663kg.
The Arms[]
- One of GD's bullets - 85.09px | 2.855m
- GD's arm's M4 - 744.54px | 24.98m
- Again, Wikipedia link up above, M4's standard length (extended stock, since that's what this one looks like, big gap between the trigger and where the stock appears to start) is 838mm or 0.838m. Scale factor is 29.81x.
- Its normal mass is 3.52kg when loaded.
- 29.813 * 3.52 = 93,220kg.
- I said 2 M4s up above, so 186,441kg for the mass of the M4s in one arm.
Like mentioned above, all guns will be assumed to be a similar length.
- Onto the M16A1. Wikipedia link above, they're typically 986mm/0.986m long. Scale factor is 25.33x.
- It's normally 4kg loaded. 25.333 * 4 = 65,032kg.
- Double since I stated 2 M16s up above, 130,064kg.
- Onto the AK-47. Wikipedia link above, they're typically 880mm/0.88m long without any folding stock shenanigans. Scale factor is 28.38x.
- The only weights on the Wikipedia page is with empty mags, so I'll assume the heaviest to try and offset this.
- 3.47kg gun + 0.33kg magazine = 3.8kg total mass. 28.383 * 3.8 = 86,903kg.
- Finally, the Mk18. Wikipedia link above, they're typically 762mm/0.762m long with the stock extended rather than collapsed. Scale factor is 32.78x.
- Wiki page doesn't specify whether the given weight is loaded or not so I'll just take it as is—2.72kg.
- 32.783 * 2.72 = 95,808kg.
- Combine these for the mass of one arm, 499,217kg.
- DOUBLE that for the mass of both arms, 998,433kg.
The... Neck?[]
- Sugi tree - 266.58px | 20m
- One of GD's bullets - 38.05px | 2.855m
- Upper frustum radius (r1) - 41.15px | 3.087m
- Frustum height (h) - 74.55px | 5.593m
- Lower frustum radius (r2) - 73.05px | 5.480m
Stick those values into this calculator, volume comes out as 330.8m3.
Multiply by 1000kg/m3, mass is 330,847kg.
The Head[]
I've overlayed a real M1911 on its head so I can properly find out the barrel length, because the full length is a bit more difficult to measure and the barrel length will still let me do the Square-Cube Law.
- One of GD's bullets - 85.09px | 2.855m
- GD's head's M1911 barrel length - 308.76px | 10.36m
- Again, Wikipedia link up above, its normal barrel length (Government model) is 127mm or 0.127m. Scale factor is 81.56x.
- Its normal mass is 1,100g (1.1kg) empty. 81.563 * 1.1 = 596,871kg.
- As mentioned earlier, cut that in half since we cannot see the lower half.
298,435kg for the head-gun.
Total Mass[]
330847.846 (neck) + 477663.335260910837211 (torso) + 998433.447954218011244 (arms) + 210850.006432554541977 (bullets) + 298435.396284420967774 (head-gun) = 2.316e6 kg.
Kinetic Energy[]
Borrowing from this accepted blog for the speed since this is literally the same sequence of panels where he's moving...
1/2 * 2.316e6 * (249,250)2 = 7.195e16 J (~17.20 Megatons; 7-B)
This is only actually 20% of the Gun Devil's mass,[2] the part that was in America's possession in-universe.[3] For a theoretical 100% GD with all its mass, the mass would just be multiplied by 5, i.e 1.158e7 kg.
1/2 * 1.158e7 * (249,250)2 = 3.597e17 J (~85.98 Megatons; 7-B+)