SAT考试是美国高中生进入美国大学的标准入学考试，包括SAT1和SAT2。SAT2是专项测验，有数学、物理、化学、生物、外语等，大部分为选择题，是可以选科的。今天我们来学习SAT2物理分析 What's a Vector，希望对大家的复习有所帮助。

　　A vector is a mathematical object possessing, and fully described by, a magnitude and a direction. It’s possible to talk about vectors simply in terms of numbers, but it’s often a lot easier to represent them graphically as arrows. The vector’s magnitude is equal to the length of the arrow, and its direction corresponds to where the arrow is pointing. Physicists commonly refer to the point of a vector as its tip and the base as its tail.