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 Mark A. Lever Dr. Mark Lever (born 1977) is a microbial ecologist who studies the role of microorganisms in the global carbon cycle. He is a professor of environmental microbiology in the Department of Environmental Systems Science in the Institute of Biogeochemical and Pollutant Dynamics at ETH Zurich. Dr. Lever earned his MA in Marine Biology at the Boston University Marine Program at Woods Hole in 2002 and his PhD in Marine Sciences at the University of North Carolina, Chapel Hill in 2008. He worked as a postdoctoral scientist at Aarhus University from 2009 to 2014, when he joined the