Final answer:
Wood's hardness and inflexibility are physical properties that arise from its cellular structure, involving a combination of cellulose and lignin, which provide strength akin to reinforced materials.
Step-by-step explanation:
The characteristics of wood that make it an excellent building material, such as being hard and relatively inflexible, especially when dried, are examples of physical properties. These properties include the tangible attributes of wood that can be observed or measured without altering the substance's chemical identity. The hardness of wood is a result of its structure at the cellular level, where lignin and cellulose combine to give wood its tensile and compressive strengths. This makes wood akin to composite materials like reinforced concrete, with the cellulose fibers providing tensile strength and the lignin providing compressive strength. Dried wood is particularly strong and rigid due to the reduction in moisture, which further limits the movement of its particles, solidifying its physical structure.