When a sculptor uses a chisel on rock, the rock undergoes physical weathering.

Here's why:

* Physical weathering is the breakdown of rocks into smaller pieces without changing their chemical composition.

* The chisel's impact and pressure cause the rock to fracture and break apart, creating the desired shape for the sculpture.

Here are some other points to consider:

* Chemical weathering is a process where rocks are broken down by chemical reactions. This is not involved in the sculptor's process.

* Erosion is the movement of weathered rock material. While the sculptor might remove material through erosion, the primary process involved is physical weathering.

Let me know if you have any more questions about rock weathering!