Dimensions: Dimensions are the basic concepts of measurement. Ex; such as length, time, T, P, etc.

Units: Units are means of expressing the dimensions.

       Dimensions à Force    Length         Time

                  Units à N          m, ft, cm,     h, min, s,

Basic Units: Units dimensionally independent, used for only one dimension. Ex; kg for mass, s for time,

Derived Units: Derived units are combination of various dimensions.

            Ex; in SI; Pressure: kg/m.s²   Pa(Pascal)

            density: kg/m³, heat capacity: Btu/1bm   ºF

System	B.E	A.E	cgs	M.K.S.	S.I.
Length	foot	foot	cm	m	m
Mass	slug	Ibm	g	kg	kg
Time	second	s	s	s	s
Temp	ºF	ºF	ºC	ºC	ºK
Heat	Btu	Btu	Cal	Kcal	Kcal
Force	Ibf	Ibf	dyne	Newton	N
Amount of Substance	Ibmole	Ibmole	g mole	kg mole	kg mole

   454 g = 1 Ib_m       2.54 cm = 1 in       1 ft = 12 in

   (Ib ; pound)   (Btu; British thermal units)

Conversion of Units

Ex: Convert 20 gal/h to m³/s.

7.48 gal = 1 ft³        1 h = 3600 s        1 ft = 12 in

35.31 ft³ = 1 m³      1 in = 2.54 cm     1 m = 100 cm

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