The fundamental entity of nature that is transferred between parts of a system in a physical change and is usually regarded as the capacity for doing work is energy.

Here's why:

* Transfer between parts: Energy can be transferred from one part of a system to another through various mechanisms like heat transfer, work, or electromagnetic radiation.

* Physical change: Energy transfer is often associated with changes in the physical state of a system, such as temperature changes, changes in motion, or phase transitions.

* Capacity for doing work: Energy is defined as the ability to do work, where work is defined as the force applied over a distance. This means that energy can be used to move objects, change their temperature, or perform other physical actions.

While other entities like matter, momentum, and heat can be transferred, energy is the fundamental entity that underlies these transfers and is directly associated with the ability to perform work.