Here's why:

* Physical weathering is the process where rocks are broken down into smaller pieces without changing their chemical composition.

* This happens through mechanical forces like:

* Frost wedging: Water seeps into cracks, freezes, expands, and puts pressure on the rock, eventually breaking it.

* Abrasion: Rocks rub against each other, grinding them down.

* Root wedging: Plant roots grow into cracks, expanding and putting pressure on the rock.

* Thermal stress: Rapid temperature changes cause the rock to expand and contract, leading to fracturing.

So, yes, physical weathering is a major force in breaking rocks down into smaller pieces, which can range from pebbles to large boulders.