Sergey Alexeyevich Chaplygin (; 5 April 1869 – 8 October 1942) was a Russian and

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

, and mechanical

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...

. He is known for mathematical formulas such as Chaplygin's equation and for a hypothetical substance in

cosmology Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe, the cosmos. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', with the meaning of "a speaking of the wo ...

called Chaplygin gas, named after him. He graduated in 1890 from

Moscow University Moscow State University (MSU), officially M. V. Lomonosov Moscow State University,. is a public research university in Moscow, Russia. The university includes 15 research institutes, 43 faculties, more than 300 departments, and six branches. Al ...

, and later became a professor. He taught mechanical engineering at Moscow Higher Courses for Women in 1901, and of applied mathematics at Moscow School of Technology, 1903. He was appointed Director of the courses in 1905. Leonid I. Sedov was one of his students. Chaplygin's theories were greatly inspired by N. Ye. Zhukovsky, who founded the Central Institute of Aerodynamics. His early research focused on hydromechanics. His "Collected Works", consisting of 4 volumes, were published in 1948.

Biography

Early life

Chaplygin was born to Aleksei Timofeevich Chaplygin, a shop assistant, and Anna Petrovna in Ranenburg (present day Chaplygin), Russia. After his father died when he was 2 years old, his mother remarried a tradesman and they moved to

Voronezh Voronezh ( ; , ) is a city and the administrative centre of Voronezh Oblast in southwestern Russia straddling the Voronezh River, located from where it flows into the Don River. The city sits on the Southeastern Railway, which connects wes ...

. There, he attended the Voronezh Gymnasium, which he graduated in 1886. Soon after, he attended the Moscow University, specializing in Physics and Mathematics, which he graduated from in 1890. There he met and was strongly influenced by Nikolai Egorovich Zhukovsky. In 1893, he published his first work, ''On certain cases of the motion of a solid body in a fluid'', for which he received the N. D. Brashman Award. After graduating from the university, he went on to become a professor there. In 1897, he published ''On the motion of a heavy body of revolution in a horizontal plane,'' which was the first to present the general equation of motion of a

nonholonomic system A nonholonomic system in physics and mathematics is a physical system whose state depends on the path taken in order to achieve it. Such a system is described by a set of parameters subject to differential constraints and non-linear constraints, s ...

. This equation is a generalisation of Lagrange's equation. In 1899, he was awarded the Gold Medal of the St. Petersburg Academy of Sciences.

Death

Chaplygin died of a

brain haemorrhage Intracerebral hemorrhage (ICH), also known as hemorrhagic stroke, is a sudden bleeding into the tissues of the brain (i.e. the parenchyma), into its ventricles, or into both. An ICH is a type of bleeding within the skull and one kind of stro ...

in October 1942.

Honours and awards

Hero of Socialist Labour The Hero of Socialist Labour () was an Title of honor, honorific title in the Soviet Union and other Warsaw Pact countries from 1938 to 1991. It represented the highest degree of distinction in the USSR and was awarded for exceptional achievem ...

(February 1, 1941) * Two

Orders of Lenin The Order of Lenin (, ) was an award named after Vladimir Lenin, the leader of the October Revolution. It was established by the Central Executive Committee on 6 April 1930. The order was the highest civilian decoration bestowed by the Soviet ...

(February 1, 1941 and December 22, 1933) *

Order of the Red Banner of Labour The Order of the Red Banner of Labour () was an order of the Soviet Union established to honour great deeds and services to the Soviet state and society in the fields of production, science, culture, literature, the arts, education, sports ...

, twice (July 10, 1927 and ?) * Zhukovsky Prize (1925) * N. D. Brashman Prize (1897) Chaplygin was elected to the

Russian Academy of Sciences The Russian Academy of Sciences (RAS; ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such ...

(the Academy of Sciences of the USSR in 1925-1991) in 1924. The lunar crater Chaplygin and town Chaplygin are named in his honour.

References

External links