Reference Frames and Work.
I. Displacement is frame-dependent, so work done is frame-dependent.
II. Kinetic energy is frame-dependent.
III. The work-energy theorem (W_net = ΔK) is valid in all inertial frames.
IV. Work done by friction is frame-independent.
V. Pseudo forces must be included in the work-energy theorem when working in non-inertial frames.
