1. Common Catenary ( सामान्य कैटिनरी ) 2.Virtual work ( कल्पित कार्य ) 3. Stable and Unstable equilibrium (स्थायी एवं अस्थायी संतुलन ) Analytical conditions of equilibrium of coplanar forces, friction. UNIT-II Simple problems on Virtual Work, Catenary, Forces in three dimensions, Poinsot’s central axis, Wrenches, Null lines and planes. NOTE : This course is valid only with registered mobile numbers. Videos by-- Dr. Kaur Singh Dhounsi M.Sc., Ph.D. ( Mathematics ) Address- 45-D ,Setia Colony Sriganganagar , Rajasthan-335001 Mob- 9414989144