I'm auditing someone's work and it seems I've found an error. We have a very simple scenario where a circular steel shaft lies on sandstone. What is the torque required to turn the shaft (the shaft is in a static position)? Torque = weight of shaft × radius of shaft × friction of steel on sandstone It seems that he has divided the total by 2 which doesn't make sense to me. Then again my physics days are way behind me. If someone could confirm that I'm crazy/lucid that would be great.