Question about these thermal expansion coefficient units (m/mK)

[kasnay]

so I have never seen this unit before. 10^-6m/mK for the thermal expansion (linear expansion). I believe this unit is micrometers divided by mili kelvins?

 

[Baluncore]

So that would be an absolute thermal expansion for a fixed length, not as a proportion of length.

 

[Dullard]

I believe it's:meters / (meter x Kelvin) (not milliKelvin)

Simplifying ('cancel' the meters), it's just a ratio of expansion per degK (in one dimension)

 

[kasnay]

okay thank you, well now my question is why did they bother putting it there if it could be cancelled?

 

[Dullard]

It may be 'cancelled' for mathematical purposes. The information that it conveys helps you to make sense of what the number actually represents. In this case, 1 micron per meter of length for every 1 DegK. I don't know if they explicitly teach dimensional analysis these days, but it is a very useful way to check the validity of your answer - particularly if you're doing something unfamiliar.