# Q & A: Textbook Errors? - Scientific Units

Q:
My current science teacher is using the Prentice Hall Physical Science book, which is the brand with the consistant inaccurate information, right? Well, I’ve got two questions. 1) He has said the kilogram is the base SI unit for mass. Well, if the liter is the base SI unit for volume and not the kiloliter, meter is the base SI unit for length and not the kilometer, should not the base SI unit for mass be, although small, the gram, NOT the kilogram? I just wanted to make sure. 2) He said lead is magnetic. I know iron, nickel, cobalt, and a few ceramic materials show magnetic characteristics, but lead doesn’t. I know it has something to do with the movement of the electrons. Is there ANY way lead can be magnetic under normal circumstances, or by any means? Thanks :D .*Chi*.
- Chilaou (age 14)
MLHS, Moses Lake, WA, USA
A:

Chilaou -

One at a time...

(1) The SI system, by definition, uses units of:

meters (distance)
kilograms (mass)
seconds (time)
kelvins (temperature)
amperes (electric current)
moles (number of atoms)
candelas (light intensity)

All other units are derived from these. For example, the natural SI units of volume are m^3 (i.e. a cubic meter, which is 1000 liters). For a very nice site that explains why these 7 units were chosen, take a look at https://en.wikipedia.org/wiki/SI_base_unit.

(2) See

-Tamara & Mats

(published on 10/22/2007)