The physical quantity measured in units of joules is energy.

Here's a breakdown:

* Joule (J): The standard unit of energy in the International System of Units (SI).

* Energy: The capacity to do work. It can take many forms, such as:

* Kinetic energy: Energy of motion.

* Potential energy: Stored energy due to position or state.

* Thermal energy: Energy associated with temperature.

* Chemical energy: Energy stored in chemical bonds.

* Electrical energy: Energy associated with electric charges.

* Nuclear energy: Energy stored in the nucleus of an atom.

So, whenever you see joules as a unit, it means you're dealing with some form of energy.