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
Effective torque Effective torque Effective Torque is often referred to as wheel torque or torque to the wheels is primarily associated with automotive tuning. Torque can be measured using a dynamometer. Common units used in automotive applications can include ft·lbf and N·m. For more on units see: Foot-pound force. The formula for effective torque to the wheels is: Tw = Te * Ntf * ηtf Ntf = Nt * Nf ηtf = ηt * ηf ... where Tw is wheel torque, Te is engine torque, N is the gear ratio, η is the efficiency, and the subscripts t and f are for