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
Janka Kupala National Theatre donations of citizens. In 1944 has been renamed in honour of classic of the Belarusian literature, poet Janka Kupala. Janka Kupala National Theatre Janka Kupala National Theatre (, Minsk) is the oldest theatre of Belarus. Also, the theatre is an object of cultural heritage of Belarus. The building of the theatre was built in 1890 by the project of architects Konstantin Vvedenski and Korol' Kozlovskiy. The main facade looks out onto the square formed by the intersection of Karl Marx and Engel'sa Street. The theatre was opened on September 14, 1920, and it is located in a building of the