As promised, here is that video on whip dynamics. Watch the whole thing, or start at 5:45 for the gist of it. The speed of sound is indeed (well done Alex and Ben!) 343m/sec or 1,234.8km/h (which for all you old timers, air force or navy people is 667 knots). The similarity with the shinai, as I mentioned at training this morning, is the 'unrolling' of the whip and how this causes the speed of the tip to increase exponentially. Our aim with the shinai is not to interfere with the whip-like potential of the shinai, by having the most rational and efficient cutting action possible. We should try to imitate the kinetic wave of the whip's motion through the way we use our body, recreating this unrolling by starting with the shoulders then continuing through our upper arms, elbows, forearms, wrists, palms and fingers. As you can see in the slow motion video of the whip with the taped segments, the unrolling movement is characterised by each section of the whip coming to re...