Re: To Slap the Ground or Not
I understand Force = Mass X Acceleration pretty well, having put that principle to use for decades in my studies of projectile punching and striking. If the arms were -penetrating- the floor, as a fist penetrates a concrete block in projectile punching, then it would make sense. But this principle does not apply to the spreading out of impact by a relaxed, falling body.
Since mats are usually nice and squishy, you likely won't do too much harm to yourself slapping them. Just don't be doing the hard slap if you are falling on hard ground! Stick to doing all your falling on mats.