How to compare physical vectors and directional scalars Do you ignore the direction when comparing the size of vectors? For directional scalars, such as acceleration 1 and - 2, which is larger? Do you want to compare absolute values?
In addition, acceleration is not a scalar with direction, it is also a vector. It is a one-dimensional vector without "scalar with direction". Any quantity with direction and size is called a vector, and scalar is a quantity without direction. Acceleration - 2 is large, because | - 2 | = 2, "module" is simply the length of this vector, The length of one-dimensional vector is the absolute value of coordinates, that is √ x ^ 2 = | x |. If it is two-dimensional, the length of this vector is: √ (x ^ 2 + y ^ 2), (in the plane rectangular coordinate system, which is the same as the mathematical derivation, X, y are the coordinates of vectors). Similarly, in three-dimensional, it is: √ (x ^ 2 + y ^ 2 + Z ^ 2), x, y, Z are the coordinates of space vectors, in the space rectangular coordinate system. In the theory of relativity, there are four-dimensional vectors, The length of vector is: √ (x ^ 2 + y ^ 2 + Z ^ 2 + (ICT) ^ 2), where I is the imaginary unit and C is the speed of light. Vector is the vector in mathematics. Comparing their size means comparing their length, that is, comparing their size without direction