This was on one of the flying newsletters I read. I think it might give the physics folks here a chuckle. patrick :) We were approaching from the east years ago in a B-727, which was famous for being able to descend very steeply, as long as it was not speed-restricted. Approach was changing from an east landing configuration to west, meaning that the airplanes over Lake Michigan were all going to end up high because of the change in plans. Controller (to a 727 ahead of us) : "If I give you STORY intersection at 11,000 feet, can you make it down from there?" 727 Pilot: "Yes, but we'll have to start down right now." Controller: "O.K., start down now; cross STORY at 11,000. Oh, and I need you to do that at 250 knots." 727 Pilot: "Hey, we can't come down and slow down at the same time." Controller (unsure who was giving him a hard time, since the 727 pilot hadn't used his callsign) : "Who said that?" 727 Pilot: "Uh, I think it was Newton." Controller (laughing) : "I guess I deserved that. O.K., which aircraft is anticipating an energy management problem?" Several of us jumped in and said, "We are!" all at the same time. As a former physics major, this one really cracked me up. One usually thinks of a comeback line like that on the drive home, instead of instantly as this fellow did.