Surface waves traveling on a block are affected how by sharp edges?

Surface waves, such as Rayleigh waves, travel along the surface of a material and their behavior can be significantly affected by the presence of sharp edges. When these waves encounter a sharp edge, they experience reflection. This reflection occurs because the change in geometry and material properties at the edge leads to alterations in the propagation of the wavefront.

Reflecting the surface waves at the edge means that some of the wave energy is redirected back into the material rather than continuing onward. This phenomenon is particularly important in nondestructive testing, as reflected waves can provide critical information about flaws and discontinuities in the material being tested.

Additionally, while wave absorption is a consideration in some scenarios, and waves may experience changes in amplitude at boundaries or material transitions, the sharp edge's role in reflecting surface waves is the most notable characteristic. Therefore, the correct conclusion is that surface waves are reflected when encountering sharp edges, thus making a strong understanding of wave behavior crucial for interpreting testing results accurately.