# What is the dimension of the physical quantities

## dimension

dimension, 1) mathematics: the dimension of a finitely producible vector space is the uniquely determined number of its basis vectors. The dimension of the vector space n is n.

2) physics: Dimension of a physical quantity, the part of a physical quantity that only contains its quality, but not its quantity. One arrives at the dimension if one disregards its vector or tensor property, all numerical factors including the sign and possibly existing references in the defining equation of the quantity. Example: Length, width, height, radius, diameter, curve length all have the dimension length, in spite of the different payments in kind. The dimension of a physical quantity is usually determined by its connection with the base quantity mass (M.), Length (L.) and time (T) described. Formally, one can express the intention to want to specify the dimension of a quantity by writing the quantity in square brackets. The dimension of the speed v is e.g. the dimension of the length divided by the dimension of the time, so:
[v] = L./T = LT- 1. (Dimensional analysis)

The term Size type (also called the kind of a quantity) also only includes qualitative properties of physical quantities; however, it is not defined uniformly. Mostly one understands by it something that one obtains from a physical quantity, if one disregards all numerical factors, but retains vector and tensor character as well as references in kind. For example, volume, moment of area of ​​the 1st degree and section modulus have the same dimension, but they are considered to belong to different types of size.