1. The problem statement, all variables and given/known data http://picasaweb.google.com/lh/photo/ChOBWTwVEO3hI0wtftmdmw?feat=directlink [Broken] A rigid rod is put in a global bowl horizontally.The bowl is shaggy.Do friction forces exist where the rod and the bowl touch? 2. Relevant equations 3. The attempt at a solution If the bowl is smooth,it's clear that friction forces don't exist.But what if the bowl is not smooth?