Physical weathering is the process by which rocks and minerals break down into smaller pieces without changing their chemical composition. This occurs due to various natural forces, such as temperature changes, freeze-thaw cycles, and the impact of wind or water. For example, when water seeps into cracks in rocks and freezes, it expands, causing the rock to fracture. Another common form of physical weathering is abrasion, which happens when rocks are worn down by friction from other materials, like sand or gravel. This can occur in rivers, where flowing water carries particles that scrape against larger rocks, gradually smoothing and breaking them apart.