We all know that Wnet= delta KE, change in kinetic energy. But how about if something has not only kinetic energy but also potential energy, no work done by nonconservative force, then how do we find the net work? Still use change in kinetic energy while ignoring PE? If something has no kinetic energy at all, but only potential energy, then I think we can not use the formula that I gave previously but find out the change in potential energy? So to what extent, Wnet=delta KE can be used? Hope you can clarify,thanks.