Measuring things like a martial artist's strike can be challenging because it is a complex motion and common vernacular will use imprecise or incorrect terms. This question is an attempt to identify the applicable measurements (quantification) and the correct units behind those numbers.
In a recent question of mine, I asked for sensors that could be used to measure a martial artist's strike, such as a kick or punch. My primary intent was to demonstrate to the student how their technique improved their strike. The answers there are great, and definitely addressed my question.
What led to this question is that I received a follow-up, clarifying comment asking if I wanted to measure force, energy, or power. To which I responded that I simply needed something measurable to show the difference or improvement to the student.
There was a subsequent comment* that got me thinking:
From what you write here, I would like to add that it is neither force nor pressure nor energy that you actually want to measure.
*The comment has since been deleted, but I started this question shortly after it was left.
What got me thinking about that second comment is while I've seen many references using units of force, there are other ways of quantifying a martial arts strike.
- This reference prefers to use 'force' and condemns using 'pressure'
- This reference also uses force, but mixes up their terminology when describing acceleration and velocity, so their usage of terminology is suspect.
- This reference focuses on velocity, momentum, and energy.
- This reference uses $lb_F$ for their measurements. Coincidentally, this is the series that started me down my original line of thought with the other question.
What is the correct terminology for measuring (quantifying) the magnitude of a martial artist's strike versus another strike?
The measurement should be applicable across a variety of strikes (punches, kicks, elbows, etc...) and valid for different practitioners. Likewise, I'm not worried about defining good versus bad; I want to be able to quantify the strike. This ties into basic process improvement - we measure the process we want to improve and compare the measured results.