According to this theorem, the work done by all the forces (conservative or non-conservative, external or internal) acting on a particle or an object is equal to the change in kinetic energy of it.
Let , ... be the individual forces acting on a particle. The resultant force is and the work done by the resultant force is:
where is the work done on the particle by and so on. Thus, work energy theorem can also be written as: Work done by the resultant force is equal to the sum of the work done by the individual forces. There are a few points worth noting:
- ) If Wnet is positive then Kf - Ki = +ve (positive), i.e, Kf > Ki or kinetic energy will increase and vice versa.
- ) This theorem can be applied to non-inertial frames also. In a non-inertial fram it can be written as: Work done by all the forces (including pseudo forces) = change in kinetic energy in non-inertial frame.