| 词条 | Draft:Sita |
| 释义 | Sita (Ѳ ѳ; italics: Ѳ ѳ) is a letter of the engineering dynamics alphabet. The shape and the name of the letter are derived from the Greek letter theta (Θ θ). However, Ѳ is pronounced "sita" exclusively in the study of particle and rigid-body kinematics. Sita is taken to be the counterclockwise angle between the positive x-axis and the position vector of a point in the xy-plane. Its first and second derivatives with respect to time are angular velocity, denoted "sita-dot," and angular acceleration, denoted "sita-double-dot," respectively. |
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