Compound lever the force of pushing back the stick to the levers and they rub against the wheels, using friction to slow and eventually stop the train. These are everyday applications of this mechanism. A piano key is a compound lever of the first-class, since the fulcrum is between the weight to be moved and the power. The purpose of this lever is to translate a small movement (depression of the key) into a larger and fast movement of the hammer on the strings. The quality of the resulting tone depends on whether the final speed is brought about by gradual or
Mark A. Lever faculty of ETH Zurich. Lever is a member of the Deep Life Scientific Steering Committee and Synthesis Group 2019 for the Deep Carbon Observatory and is an associate editor for "Frontiers in Microbiology". In his research, Dr. Lever investigates factors that determine the presence, abundance, community composition, and metabolism of microorganisms in aquatic sediments and in Earth's crust. In 2013 he discovered that microbes survive deep in the crust by living off of chemical energy in the “dark biosphere.” His work has a special focus on the burial, remineralization, and synthesis of organic matter in aquatic sediments and in Earth’s