Of           

Standard—an exact quantity that people agree to use for comparison

·       English system: standard units include inches, feet, pounds (US)

·       Metric system: standard units are meters, grams (rest of world)

·      SI system =International System of Units—an improved version of the metric system used by scientists worldwide

 

To measure…	You would use…	The base unit is…
Length (distance)	ruler, meter stick	meters (m)
Mass	triple beam balance	kilograms (kg)
Time	stopwatch	seconds (s)
Temperature	thermometer	Kelvins (K)
Volume	graduated cylinder	liters (L)

 

All measurements must have a NUMBER and a UNIT!

Mass—the amount of matter in an object

Volume—the amount of space an object occupies

·      Volume = length * width * height

·       1 cm cube: Volume = 1cm*1cm*1cm = 1cm³ = 1mL

·      This is called a derived unit because it is calculated using base units.

The SI system is easy to use because it is based on multiples of 10. 

·       Prefixes are used with the units to tell which multiple of 10 to use.

·       Example: “kilo” means 1,000, so a kilometer is 1,000 meters.  Easy!

Prefix	Symbol	Means
kilo-	k	1,000
centi-	c	0.01   (or 1/100)
milli-	m	0.001 (or 1/1,000)

(More prefixes are on p. 15 of the book)