On 08/30/2012 08:09 PM, nestork wrote:

PS: Also, no one knows why, but friction is speed dependant. It takes
less total work to zip a drywall screw into a stud with a drywall gun
than it does if you wrist twist the same screw into the same stud by
hand. We don't have a "theory" of friction that would explain why.

Maybe static vs. kinetic friction?

http://en.wikipedia.org/wiki/Friction#Static_friction

Jon