The symbol "Ns" is not used to represent the dimension of momentum. The dimension of momentum is typically represented as "kg∙m/s" in the International System of Units (SI).
In SI units, momentum is defined as the product of mass and velocity. Mass is measured in kilograms (kg), and velocity is measured in meters per second (m/s). When you multiply these two quantities together, you get the unit "kg∙m/s," which represents momentum.
The unit "Ns" represents a different physical quantity known as impulse. Impulse is the change in momentum of an object, and its dimension is equivalent to the dimension of momentum. So, "Ns" can be used to represent the dimension of impulse, but not momentum itself.
To summarize, the dimension of momentum is "kg∙m/s," while "Ns" is the dimension of impulse.