Here's why:

* Physical Science Definition: Physical science encompasses the study of the non-living world, including the fundamental laws governing matter and energy.

* Physics Focus: Physics is the study of the fundamental laws governing the universe, including matter, energy, motion, forces, and their interactions.

* Relationship: Physics provides the foundational principles that underpin many other branches of physical science, such as chemistry, astronomy, and geology.

In essence, physics is the bedrock upon which other physical sciences are built.