If the total work done is calculated using the area of the closed curve (Force vs Displacement), then the formulation doesn’t care if the force is conservative or not. Is that right? For instance, if I understand it right, spring force is a conservative force and hence work done by the spring in bringing a mass back to its original position should be zero. However, if we are able to plot spring force against displacement, we surely have a non-zero area under it. My essentially question is can the work done by a non-conservative can be calculated by area under Force vs Displacement curve? Is that right? So when we calculate work done by a gas in piston as area under PV curve of the thermodynamic cycle, this is because gas force is a non-conservative force?