THERE IS AN INTERNATIONALLY ACCEPTED SYSTEM FOR MEASUREMENT UNITS CALLED SI, OR SYSTEME INTERNATIONAL FOR SHORT. OVER THE NEXT SEVERAL YEARS, WE SHALL BE CONTINUALLY EXPANDING OUR KNOWLEDGE OF THIS SYSTEM AND THE PARAMETERS THAT IT DEFINES.
LENGTH
The standard unit for measuring
lenght is the meter. You need to become comfortable with this unit
of measure for linear distance and some of its divisions, namely:
centimeter = one/hundredth of a meter.
There are 100 cm in a m
millimeter = one/thousandth of a meter.
There are 1,000 mm in a m
kilometer = 1,000 meters. There
are 1,000 m in a km.
You will be asked to measure a number of objects
in class and to express their dimensions in millimeters (mm), centimeters
(cm) and meters (m).
Remember, if an object is 10.7 cm long, that
is the same as 10 cm and 7 mm although we would not commonly express it
in such a cumbersome way. Similar, we would say that we have to travel
10.5 km and not 10 km and 500 m-but it would be correct if we decided to
do so.
MASS
The standard unit for measuring
mass is the kilogram. You need to become comfortable with this unit
of measure for mass and some of its divisions, namely:
gram = one/thousandth of a kilogram.
There are 1,000 g in a kg.
milligram = one/thousandth of a gram.
There are 1,000 mg in a g and 1,000,000 mg in a kg.
TIME
The standard unit for measuring
time is the second. There are 60 seconds in a minute and 60 minutes
in an hour.
You need to know how we came to define a day,
month, and year.
TEMPERATURE
The
standard unit for measuring the temperature of a material is the degree.
However, there are several kinds of degrees. In common, everyday
life we use the Fahrenheit scale where water freezes at 32o
and boils at 212o.
For scientific purposes, this system is not
used. Rather, we use the Celsius scale in which water freezes at
zero and boils at 100o. IN CLASS, WE SHALL ALWAYS WORK
IN UNITS OF CELSIUS, EVEN IF IT IS NOT SPECIFICALLY STATED.
VOLUME
The
standard unit for measuring volume is naturally derived from units of measuring
length. Thus, a cube that is 1 cm on each side is a cubic cm or cc3.
This is an excellent unit for measuring the volume of a liquid. We
commonly refer to a small liquid volume as x cm3 or milliliters (ml).
Larger, liquid volumes are expressed in liters
(l). A liter is made up of 1,000 ml or 1,000 cubic cm.