10-15 seconds of surge = x ammount of boost pushing back for 10-15 seconds of mayhem.
Off throttle surge = x ammount of boost in a given volume leaking back through the compressor, obviously diminishing pressure quickly over time, thus also force. You thought you were being smart with your pedanticism over the term "force", you have failed.

Also, explain to my why metal which is already hot "probably" won't have it's temperature affected by friction. I thought you did mechanical engineering???