If work is displacement times force, lifting a weight up and bringing it down to the same spot would have zero displacement, and thus zero work is done. However, isn't work a path function? In thermo we learned that heat and work were path functions while quantities such as internal energy and enthalpy were path functions. So by thermo reasoning, the work done in the case described above would NOT be zero since work is a path function, but the definition of force as displacement times force says it would be zero. What am I missing here? Would the same reasoning apply to running around a track, where the person ends at the same spot as they started? Thanks!