Aelfinn, "Dante vs Itachi Uchiha"
"Anyway, 6600 pounds is probably a good place to start, but I’m going to use the Savior’s fist in this (which might take a lot of time). Anyway, in this post I simply wish to define some parameters.

Based on this video, at around the sixminute mark:
http://www.youtube.com/watch?v=F0PZaLOzQYThere are (lowend) five “cubic Dante’s” worth of stone in the hand alone. I’m wildly underestimating, and that’s just an assumption, but there it is.

Anyway, assuming Dante is 6foot3, that puts him at around 1.9 meters tall, and a “cubic Dante” is about 6.8 cubic meters. Five “cubic Dante’s” is a little more than 34 cubic meters.

Now, from this site, stone is (lowend) 2300 kg per cubic meter.

http://www.engineeringtoolbox.com/densi ... _1265.html
Converting from kilograms to pounds to Newtons (using Google), results in 773,532.394 Newtons. Quite a lot.

This is effectively a “lifting strength”. Now, even though lifting strength and striking strength are relatively closely related and use similar muscles, I’m going to divide by 8 (for example, the average bicep curl is onefourth the average benchpress). This is 96691.5 Newtons."

Continued:
"To quote myself from another thread:

“Anyway, the length of the average forearm is 15.7% the length of the body, which is, on average, 173.1 cm. This means the average forearm length is about 0.272 meters.

http://www.exrx.net/Kinesiology/Segments.html
The weight of the forearm is 1.87 percent of the body, which means it weighs about 1.4 kg, which is also located 43% of the forearm’s length away from the elbow. This is about 0.12 meters away from the elbow.

1.4 kg that are 0.12 meters away from the fulcrum is a Torque of 1.6 Newtonmeters. Holding a 1.5 kg sword and a 0.48 kg hand 0.272 meters away from the elbow is a Torque of about 5.3 Newtonmeters. That is a total of about 7 Newtonmeters resistance.”

I’ll bump that up to 10 Newtonmeters, as those measurements might be low for someone tallerthanaverage like Dante. Now, taking into account that the bicep attaches at ~4 cm from the elbow, the “striking strength” times 0.04 – 10 is equal to more than 3857.66 Newtonmeters.

Angluar acceleration is Torque divided by Moment of Intertia.

en.wikipedia.org/wiki/Angular_acceleration

Moment of Inertia is mass times radius squared.

en.wikipedia.org/wiki/List_of_moments_of_inertia

The moment of inertia, overestimating a little bit, is going to be about 0.3042. The Torque divided by that is about 12681.

This creates an angular acceleration of 12681 radians/sec^2.

Knowing that position is the second integral of acceleration, an equation can be found wherein (final radian = 6340.66*t^2). I will assume that a swing is 120 degrees or 2pi/3 radians.

This results in a swing time of 0.000330 seconds.

Further math could be done to see how fast the end of the sword was going."

"en.wikipedia.org/wiki/Arc_(geometry)

Using this, the distance Dante’s hand traveled (assuming 0.3 meters distance from elbow) would equal (2pi/3) times 0.3, which results in 0.628 meters.

That distance traveled in 0.000330 seconds is about 1902 m/s, or more than Mach 5. Assuming there is a sword extending two meters from the elbow, however, results in a speed of about Mach 17."

"Uuuuuuuuuuhhhhhhhhh FUUUUUUUUUCKKK.

Alright, guys. I made a slight mistake. Not an overestimation, but an underestimation. I don’t know what happened, but I am checking my math again. Check it yourself, if you can. I want to make absolutely sure. What I am getting is this:

A 1.1 meter sword would be moving at MACH 20 WITHOUT accounting for the length of the forearm.

Including the forearm puts it at almost Mach 26."
Aelfinn fixed this, and found a mistake in his math:
"False alarm, guys. This isn’t easy for me to admit, but I made a huge mistake.

I miscalculated the time of the swing. It’s actually the square root of 0.000330.

This means that Mach 20 is just wrong following this method. It isn’t even Mach 1.

I’m sorry."
Here's scaling it: 0.000330x=1
1/.000330=x
x=3030.3 sword swings per second.
Impressive if the calc holds.