# Why isn't kilogram written as square kilogram ($\mathrm{kg^2}$) but meter is? [closed]

I was wondering why some notations can be written with square and some can't.

• This question is unclear – Alfred Centauri Dec 1 '16 at 1:43
• There's no reason why some units couldn't contain mass squared, see e.g. en.wikipedia.org/wiki/Gravitational_constant – Gert Dec 1 '16 at 1:59
• I'm not sure what you're asking. Kilogram isn't written as kg^2, because it's written as kg. Meter is not written as m^2 because it's written as m. Square kilograms are written kg^2 and square meters are written m^2. – Cort Ammon Dec 1 '16 at 3:55

## 1 Answer

There is no reason why a quantity cannot be defined in units of kg-squared.

For example, gravitational attraction depends on the product of 2 masses; this product could be given a name and quantified in units of $kg^2$. Likewise the magnetic force between two current-carrying wires depends on the product of the currents; this product would be measured in the unusual units of Amps-squared ($A^2$). This combination does in fact occur quite often within electo-magnetic units, but it has no special significance and no name.

The reason we don't do this already is that it is not useful, unlike $m^2$ for area and $m^3$ for volume, which are useful quantities.