Lu, I enjoy your contributions and unique perspective to these questions. Lurking is fine, but if you have a question that you don't want to post, just email me.
Flight Safety, that sounds good. Another way of looking at the .5g door example is that the mass of the man is added to the mass of the door, so the force on the spring is greater. Actually it's the same way that you explained it, I just find this one a bit easier to picture.
You said, "BTW, this particular thread and the debate contained within it has been great fun."
Yes, same for me. That's why I participate.
Happy New Year!
[ 01 January 2002: Message edited by: heedm ]</p>