JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Work Depends on Frame of Reference

With change of frame of reference (inertial), force does not change while displacement may change. So the work done by a force will be different in different frames.

Examples : (1) If a porter with a suitcase on his head moves up a staircase, work done by the upward lifting force relative to him will be zero (as displacement relative to him is zero) while relative to a person on the ground will be mgh.  

(2) If a person is pushing a box inside a moving train, the work done in the frame of train will \[\overrightarrow{F}.\overrightarrow{s\,}\] while in the frame of earth will be \[\overrightarrow{F}.\,(\overrightarrow{s\,}+{{\overrightarrow{\,s}}_{0}})\] where \[{{\overrightarrow{\,s}}_{0}}\] is the displacement of the train relative to the ground.