Godzilla's Atomic Breath
And here it is, the succulent meat of the film being served!
Speed
There are quite a few appreciable AB-related velocity calcs to cover now, so I'll try to limit the word count only to as much as necessary.
Beam #1
http://i.imgur.com/b2bv33h.png
6/24 = 0.25 seconds
222.89/0.25 = 891.56 m/s (Mach 2.62)
Beam #2
http://i.imgur.com/IMxrLd3.png
0.25 seconds again.
139.57/0.25 = 558.28 m/s (Mach 1.64)
Beam #3
http://i.imgur.com/29atV84.png
There has never been a Japanese battle cruiser issued or renamed as the Aizu for direct comparative purposes; fortunately, battle cruiser dimensions appear to be standardised at 222 metres.
16 frames is the duration from the beam emerging on the far side of the Aizu to reaching the other end of the screen.
16/24 = 0.67 seconds
1354.97/0.67 = 2022.34 m/s (Mach 8.59)
Beam #4
http://i.imgur.com/qto1dZc.png http://i.imgur.com/AcTPZoo.png
IMDb profile on the actor cited in the first link, for the height source.
Beam clarity is a minor issue in this particular feat: as a result, the energy-transmitting timespan is set on a range between 4-6 frames.
Low-End
6/24 = 0.25 seconds
351.21/0.25 = 1404.84 m/s (Mach 4.13)
High-End
4/24 = 0.17 seconds
351.21/0.17 = 2065.94 m/s (Mach 6.07)
In conclusion: the propagation velocity of Oni Godzilla's Atomic Breath varies between barely supersonic to close-to-high hypersonic levels: the mean would be in the borderline hypersonic range.
King Ghidorah's Gravity Bolts should match up with the AB in terms of speedscaling.
Firepower
Thanks to a D-03 Missile being fired from inside Oni Godzilla's body (long story, watch the film) and piercing out through its neck, when its attempts to fire more ABs, the radiation energy leaks out of the open wound instead, steadily reducing the daikaiju's structural integrity before a third attempt finally results in near-total disintegration, with only its heartsurviving the last blast.
With zero traces of even minimal bodily debris or fleshy scraps remaining within the local vicinity of the heart, and given the thermonuclear properties of the Atomic Breath, I have concluded that the most probable scenario of self-destruction was the almost complete vapourisation of Godzilla's flesh.
Taking a couple of cues from a previous calc of mine regarding biomass vaping:
I suspect I would not be successful in precisely pinning down on an accurate result even with my "search engine wizardry" for vape energy values of a reptilian counterpart, so I did go for a placeholder of sorts: namely, the minimum energy per mass consumption required to entirely vapourise the core consitituency of elements composing the human body (I'm uncertain if the relative water:carbon ratio in animal bodies holds up as largely consistent across most terrestrial/amphibious vertebrate species, but any attempts at resolving the issue without expiring too much time had been unsuccessful).
The result was 8509.43 J/cm^3.A combination of basic investigative skills and the wonderful accessibility of Google Search enabled me to find not one, but two supremely appropriate RL equivalents to potentially deciphering the density of a daikaiju with predominantly reptilian physiology (thanks to the large-scale assimilation of Godzilla DNA, I think it would be fair to classify post-mutation Orga in a similar vein to the Big G itself).
Source for both crocodile (archosaurian reptile) and chicken (avian [direct dinosaurian descendent]) densities. I personally chose to solely continue the calculation with the adult crocodile density of 948 kg/m^3 for reasons I've yet to entirely comprehend for myself. Feel free to explore the other routes and avenues for yourself, though!Oni Godzilla weighs 30,000 metric tons
Volume = Mass (kg)/Density
V: 30,000,000/948 = 31,646 m^3.
31,646*1,000,000*8509.43 = 2.692894218e+14 joules or 64.36 kilotonsof TNT equivalent.
It took 3 AB misfires to finally reduce Godzilla to a sufficiently vulnerable state for bodily vapourisation, but only one was necessary for the actual process; after absorbing Mothra's and Baragon's spiritual essences, King Ghidorah can set up energy barriers durable enough to tank, absorb and reflect back Godzilla's beam attacks.