Hardness Hardness Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. Some materials (e.g. metals) are harder than others (e.g. plastics, wood). Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: "scratch hardness", "indentation hardness", and "rebound hardness". Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter. There are three
Performance-enhancing substance of which were former Olympic athletes with the other four elected from independent companies. This is the United States Anti-doping Agency and have the ability to test athletes across the nation. Steroids and performance-enhancing drugs are used across all sports organizations around the world. Performance-enhancing substance Performance-enhancing substances, also known as performance-enhancing drugs (PED), are substances that are used to improve any form of activity performance in humans. A well-known example involves doping in sport, where banned physical performance–enhancing drugs are used by athletes and bodybuilders. Athletic performance-enhancing substances are sometimes referred to as ergogenic aids. Cognitive performance-enhancing drugs, commonly