mechanical engineering handbook

[...]... situation Within the constraints of a single book on mechanical engineering, it provides overviews of topics with modern perspectives, illustrations of typical applications, modeling to solve problems quantitatively with realistic simplifications, equations and procedures, useful hints and reminders of common errors, trends of relevant material and mechanical system behaviors, and references to additional... where the subscripts refer to individual forces or couples and the corresponding displacements, ignoring frictional effects Mechanical Efficiency of Real Systems Real mechanical systems operate with frictional losses, so input work = useful work + work of friction ( output work ) The mechanical efficiency η of a machine is η= output work useful work = input work total work required 0 < η .