Mechanical energy swing because of the work done by the pendulum to oppose these non-conservative forces. That the loss of mechanical energy in a system always resulted in an increase of the system's temperature has been known for a long time, but it was the amateur physicist James Prescott Joule who first experimentally demonstrated how a certain amount of work done against friction resulted in a definite quantity of heat which should be conceived as the random motions of the particles that comprise matter. This equivalence between mechanical energy and heat is especially important when considering colliding objects. In an elastic collision,
What a Pushkin, what a son of a bitch! year: What a Pushkin, what a son of a bitch! "What a Pushkin, what a son of a bitch!" (; sometimes separated by exclamation mark instead of comma) is a catchphrase and winged word from Alexander Pushkin's correspondence with one of his friends, poet Pyotr Vyazemsky. The phrase commonly expresses a joy after finishing one's work and appears particularly in several Russian literary works. In a letter dated circa November 7 or beginning of October, 1825 Pushkin, celebrating his finished drama "Boris Godunov" wrote to Vyazemsky: That was preceded by what Pushkin wrote to Vyazemsky on July 13 of the