A whole can of worms indeed. I'd throw in my two bits here though I'm not a Kenpoist (could be someday... :uhyeah: ) But there were several things I recall from Parker Jr's seminar that (MAYBE) I failed to interpret correctly or (MAYBE) you were distracted by watching his demonstration instead of what he was saying :idunno: who knows and it don't really matter.
1) What is power? I liked Golden Dragon's answer thus far.
2) Is it physical, psychological, mental, or a combination? A combo, combining the three to work together in harmony.
3) Is it more than "chi"? In some ways it
is chi/ki strength from within. The Force!
4) When people say "do it with power", what does that mean? To me it means that you can hit/kick something and have little or no effect, or you can kick/hit something and actually show a result, or you can hit/kick something and totally destroy it. Doing it with power is doing it with enough force to achieve your desired result.
5) Can power be present with muscle tension or in a relaxed state? Either, but one generates more force than the other.
6) How can being "relaxed" generate more power? This is going to be my longest answer... and one where I'll (paraphrase) Parker Jr. from his seminar we attended. Parker demonstrated the effects of hitting with tension and hitting while relaxed. You recall that the (20 something yr. old volunteer) said that he felt the tension hit just on his pecs alone... but the "relaxed" hit he felt go totally through him. Parker Jr. used the analogy of automobiles to help articulate his point. A car traveling at 55mph is about to hit another car that is going 30 mph. The driver of the car (going 55) might hit the brakes and thus apply tension thus slowing down the momentum of the car and also reduce the force of impact. OR the driver can just simply continue without using any brake and hit the car at the speed he is travelling. Which will cause the more damage? Of course, the latter. Why? Because of momentum.
Thus, you throw a punch at whatever speed you choose but your muscles are relaxed all the way to just the moment before impact. All that force is still being generated and travelling without being slowed from tension of the muscles which is (of course) nothing more than a contraction and pulling back thus slowing you down thus reducing the "power" of your punch. Parker Jr. said that you tense up at the last possible second before hitting your target, more to protect your hand than to generate any force. Also being relaxed helps not wear you out in a prolonged altercation. Parker Sr. mentioned a bit about muscles and understanding how they work in Book 2 of his Infinite Insights.
7) Are there more than one type of power? If not, is power just one type, but handled differently? Yes, there is physical, mental and emotional power. How each are applied determines their strength (respectively). You can use your mental powers to talk, think your way out of a fight/altercation. Parker Jr. said that by talking your way out of a fight is being a lot better than one who beats down their opponent.
Emotional power is inner strength, inner will, being able to "be strong" in trying circumstances. Not "curling up into a fetal position" (inside) and facing the hurt, anger or whatever. Other words...dealing with it.
Physical power was just recently described by goldendragon.
The above was just my own opinions (except of course where I (loosely) paraphrased GM Parker (and agreed with goldendragon

. Deal with it. :asian: :wink1: