The texture of a rock surface affects how fast it physically weathers by water because a rough surface provides more surface area for water to interact with, leading to faster weathering. On the other hand, a smooth surface has less surface area for water to work on, thus slowing down the weathering process. Additionally, the presence of cracks or fissures in the rock surface can also accelerate weathering as water can penetrate deeper into the rock, causing it to break apart more easily. Overall, the texture of a rock surface plays a significant role in determining the rate at which it weathers when exposed to water.
