ARDMS Ultrasound Physics & Instrumentation Practice Exam

What property of an object describes its ability to resist compression?

1. Density

2. Stiffness

3. Elasticity

4. Sonic speed

The correct answer is: Stiffness

The property that describes an object's ability to resist compression is referred to as stiffness. Stiffness quantifies how much a material deforms under a given load—or compression—indicating how rigid the material is. A stiffer material will exhibit less deformation when a compressive force is applied, demonstrating greater resistance to being compressed. In contrast, density relates to the mass per unit volume of a substance and does not directly indicate how much that substance can withstand compression. Elasticity refers to the ability of a material to return to its original shape after deformation, which is relevant but distinct from simply resisting compression. Sonic speed, on the other hand, is a measure of how fast sound waves travel through a material and is influenced by both stiffness and density, but does not reflect the material's ability to resist compressive forces directly.