数学中的“+”“-”号应该大致表达两种含义:一是用来表示运算符,一是用来表示数字的大小,然而物理学中“+”“-”号的含义要远远大于这些.要让学生能清楚的明白其中的奥妙,确实颇费周折:矢量是既有大小又有方向的物理量,学生在进入高中以前只认识到标量,或者即使接触到矢量如: The “+” and “-” signs in mathematics should generally express two kinds of meanings: one is used to represent operators, and the other is used to represent the size of numbers. However, the meaning of “+” and “-” in physics is far greater. For these students, it is really troublesome for students to clearly understand the mystery: Vectors are physical quantities that have both size and direction. Students only recognize scalars before entering high school, or even if they come into contact with vectors, such as: