Here's why:
* Dimensions represent fundamental quantities: Dimensions like mass (M), length (L), and time (T) are used to describe the fundamental nature of a physical quantity. They are always positive.
* Derived quantities are built from fundamental quantities: Derived quantities like velocity (LT⁻¹) or density (ML⁻³) are combinations of fundamental quantities, and their dimensions are determined by the combination of the fundamental dimensions.
Example:
* Force: Force has the dimension of mass (M) multiplied by acceleration (LT⁻²), resulting in the dimension ML⁻¹T⁻². This shows that force has a positive dimension of mass.
While there might be specific contexts where a quantity appears to be "negative" with respect to mass, this is typically due to a chosen convention or mathematical representation rather than a fundamental negative dimension.
Let me know if you have a specific example in mind, and I can help you understand it better!
