by **Guest** » Sun May 13, 2007 11:37 pm

I can't help with this one. I don't know what ct is the symbol for (some local unit?) but it is nothing I can convert to centimeters.

71 ct = cm

I have grouped the others by underlying principle.

These are all examples of SI prefixes, which are merely other ways of expressing powers of ten.

Hecto- is the prefix for 100, so 1422 g = 14.22 x 100 g = 14.22 hg. You have to learn to recognize all the prefixes as their power of ten.

1422 g = hg

3.25 hPa = kPa

39 pF = nF

0.96 kN = mN

9.456 Hz = mHz

821 ÂµA = aA

0.96 kN = mN

24.65 MΩ = TΩ

On this last one, you have to express both terms in the same unit before you can add.

84 kV + 35V = MV

The SI has a few odd conversions that are not powers of ten. Kelvin is the unit of absolute temperature and 0Â°C = 273.15 K. There are 60 s in 1 minute, so 150 s = 2.5 min. All you can do is memorize them, but rejoice there aren't as many odd factors as in the Imperial/Customary system still somewhat used in the UK and US.

The SI has several "derived" units which are an extension of physical principals. C is coulomb, the unit of charge, and and a charge flow 1 C/s is by definition a current of 1 A. Similarly, power is the rate of flow of energy and 1 J/s = 1 W, and energy is force times distance over which it acts. If your school has not taught you these concepts, I recommend downloading the SI Brochure from the BIPM in France (text is available in English and French.) to understand the SI system of measurement.

5379 A.s = C

16 mW = J.s-1

13 GN.m = kJ

7 W.s + 65 cW.s = J

318 Bq = s-1