The physics textbook i'm working with doesn't seem to give me the required background for working with and understanding SI and derived units. Here is an example of something i am struggling with: In studying fluid resistance, the book starts by displaying 2 equations. 1 is for fluid resistance when the object is at low speed and is f = kv (5.7) The other is for when the object is at high speed and is f = Dv^2 (5.8) In this case with the constants k and D my book has this to say: You should verify that the units of the constant k in Eq. (5.7) are N x s/m or kg/s and that the units of the constant D in Eq. (5.8) are N x s^2/m^2 or kg/m So the problem I'm having is that i see one of the two SI derived units (in bold) and i try to make sense of it intuitively. Like how a velocity = m/s, i can clearly imagine that it is the amount of metres travelled in a given length of time. But I have no idea where to start for intuition for these. My thought process For N x s/m, I read that as "newton seconds per metre". So fiirstly, newton-seconds: that's the amount of seconds for which a newton force is applied? And then i try to conceptualize dividing that along a metre and i cant conceptualize it. Is it the quantity of newton-seconds that "pass" in the travel of an object through one metre of fluid? Edit: I thought i read that it was called dynamic viscosity, but on second inspection that would be m^2 Anyway, my general issue as evidenced above is my lack of certainty about how i should treat derived units: whether i should try to visualize them intuitively or what. Also which resources i could use to gain practice and understanding with working with these units.