I've been trying to figure out how to know what units can be used with each other in equations such as P=E/t. After reading about the MKS, CGS, and FPS unit systems, I think I understand now, but Im not sure.

 

1)

From what I understand, the MKS, CGS, and FPS unit systems are collections of units that can be used in equations with only other units from the same collection. So if you use MKS, you can use meters with kilograms, but not meters with grams to get the right answer. In MKS you can use kelvin but not celsius, you can use watts but not statwatts, etc... Im I understanding right so far?

 

2)

If I was to use a set of units that aren't a part of MKS, CGS or FPS system, such as a ton instead of a pound, then how would I go about finding the other units that I must use with it in equations? Is a unit system simply just a collection of 7 base units, and all the rest of the units are just simply derived from those 7?

 

3)

Also, I seem to only be able to find a complete list of MKS units. I can't find a complete list of CGS or FPS units. I think there is three versions of the FPS system, but I can't find any. I did come across a site that showed to units from the three different versions of the FPS system though: pound/pound, pound/poundal, and slug/pound.

MKS units have morphed into SI units , or the standard international units, which is probably a part of the reason why you can easily find a complete list of those but not others.

 

onlineconversion.com is a useful unit conversion tool

Ya, I noticed that. It took me awhile te realize the difference between SI and metric, since so many websites confuse the two terms.

 

I've made my own conversion program, which I think has 74 categories, so I don't have any problem with that. I also have WinConverter which is the best shareware converter I've found.

http://physics.nist.gov/cuu/Units/