DC Motors, Part IX:  Solved example on Shunt DC Motor (part a),  8/12/2013
Channel: Lutfi Al-Sharif
Date: 2013-12-09

(*link to accompanying pdf file below*)  This series of three videos (Parts IX, X and XI) present the solution of a problem on a DC motor at different torques and thus different speeds.  It is based on the fact that as the speed changes, the back emf changes.  The ratio any two speeds is equal to the ratio of their corresponding back emfs.

http://www2.ju.edu.jo/sites/Academic/l.sharif/Material/Electrical%20Machines%20for%20Mechatronics/04%20DC%20Motors/example%206_1.pdf