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
Ahmed Janka Nabay Ahmed Janka Nabay Ahmed Janka Nabay (January 5, 1964 – April 2, 2018) was a Sierra Leonean musician and a major figure in Bubu Music, a traditionally Temne music which is played by up to 20 musicians blowing into bamboo pipes of different sizes. He first earned attention after performing for an audition of SuperSound. Janka Nabay recorded his album in Forensic Studios in Freetown during the Sierra Leonean Civil War. Since moving to Washington, D.C. in 2003, Janka Nabay has continued to play bubu music, including a performance at the CMJ College Music Marathon in New York in 2009