Certified Forester Practice Exam

What characterizes bending stresses in wood?

1. They cause the wood to fracture

2. They occur when pressure induces bending

3. They are only present in hardwoods

4. They increase the tensile strength of the wood

The correct answer is: They occur when pressure induces bending

Bending stresses in wood are fundamentally associated with the application of force that induces a bending moment. When an external load is applied to a beam of wood, it creates an internal distribution of stresses; specifically, it generates both tensile and compressive stresses across the wood's cross-section. This bending occurs when pressure or weight is applied perpendicular to the grain, leading to deformation. This fundamental principle of mechanics illustrates that when wood fibers are subjected to bending, some fibers experience tension while others experience compression. Recognizing this relationship between the applied pressure and the resultant bending is critical for understanding wood behavior in structural applications. Thus, the defining characteristic of bending stresses is their development as a direct result of pressure that leads to bending, making it essential in both structural analysis and the design of wooden structures. The other options fail to capture this critical mechanical interaction.