一、应用公式时,必须明确各物理量的符号匀变速直线运动的公式均是矢量式,运算时必须遵守矢量运算法则,即平行四边形定则,由于公式中涉及的物理量的方向均在同一直线上,因此常设此直线上的某一个方向为正方向,凡矢量的方向与之相同者 First, when applying the formula, it must be clear that the formulas for each physical quantity are uniform and the straight-line motion formula is vector-type. When operating, the vector algorithm must be followed, that is, the parallelogram rule, since the directions of the physical quantities involved in the formula are all on the same line. , so a certain direction on this straight line is a positive direction, where the direction of the vector is the same