Question

Under what conditions is work energy-theorem applicable?

Answer 1

The work-energy principle is valid regardless of the presence of anynon conservative forces. As long as you are using the work done by the resultant force (and resultant moment when involving rigid bodies) in the equation (or equivalently adding the work done by each force/moment), the work energy principle is valid.


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Answer 2

Work energy is only applicable when the chamge in kinetic energy is equal to the work done