How to Find the Sweet Spot of a Katana for Cutting

In Japanese swordsmanship, we’re taught to cut with a part of the katana called the monouchi, which is loosely defined as one third of the blade from the tip. But where exactly on the monouchi is the sweet spot?
What is the COP (Center-of-Percussion) and does it matter? bit.ly/21dvxhm
Dojo etiquette disclaimer: if your sensei teaches you a different way, please follow the instruction of your own sensei.