San (letter) San (letter) San (Ϻ) was an archaic letter of the Greek alphabet. Its shape was similar to modern M, or ϡ, or to a modern Greek Sigma (Σ) turned sideways, and it was used as an alternative to Sigma to denote the sound . Unlike Sigma, whose position in the alphabet is between Rho and Tau, San appeared between Pi and Qoppa in alphabetic order. In addition to denoting this separate archaic character, the name "San" was also used as an alternative name to denote the standard letter Sigma. The existence of the two competing letters Sigma and San is
Torque the definition used in US physics in its usage of the word "torque". In the UK and in US mechanical engineering, torque is referred to as "moment of force", usually shortened to "moment". In US physics and UK physics terminology these terms are interchangeable, unlike in US mechanical engineering, where the term "torque" is used for the closely related "resultant moment of a couple". "Torque" is defined mathematically as the rate of change of angular momentum of an object. The definition of torque states that one or both of the angular velocity or the moment of inertia of an object