|
The ABC Study Guide, University education in plain English alphabetically indexed. Click here to go to the main index |
|
|
Measurement, Decimals and the Metric System |
|||
Measure
To measure something is to calculate how large it is, or how much of it
there is, by comparing it with a fixed unit or with an object of a fixed
size.
The Decimal System
The decimal system is the most widely used system of calculation and
measurement. Decimus is Latin for tenth, and the decimal
system is based on the number ten.
The Metric System
Metric is a French word related to the French word for
measure.
The metric system is a
decimal
measuring
system that was made law in France during the
French Revolution (adopted 1795)
and is now used throughout
the world.
The metric system uses the
metre
(a unit of
length) as its basic unit. The
litre
is its basic unit
of capacity, and the
gram
its basic unit of weight or
mass.
Metre
My leg is about a metre long, but the inventors of the metric system
wanted something far more reliable than legs and arms as the
fixed unit
of their measurement. They chose the surface of our planet Earth.
A metre was defined as one ten-millionth of an imaginary line drawn
from the north pole (through Paris) to the equator. This length was
calculated, and a platinum bar of that length kept in Paris as the
practical standard for legal purposes.
1 millimetre is 0.1 of a centimetre
1 centimetre is 0.1 of a decimetre
1 decimetre is 0.1 of a metre
1 metre is the basic unit of measure
1 decametre is 10 metres
1 hectometre is 10 decametres
1 kilometre is 10 hectometres
Litre
A litre is the basic unit for measuring volumes in the metric system.
It is defined as a cube with sides that are one-tenth of
a metre
long.
1 millilitre is 0.1 of a centilitre
1 centilitre is 0.1 of a decilitre
1 decilitre is 0.1 of a litre
1 litre is the basic unit of volume
1 decalitre is 10 litres
1 hectolitre is 10 decalitres
1 kilolitre is 10 hectolitres
Gram or Gramme
A gram (French for small weight) is the basic unit for weighing things
in the metric system. It is defined as the weight of a cube of distilled
water (at 4 degrees centigrade) with sides that are one-hundredth of
a metre
long.
1 milligram is 0.1 of a centigram
1 centigram is 0.1 of a decigram
1 decigram is 0.1 of a gram
1 gram is the basic unit of weight
1 decagram is 10 grams
1 hectogram is 10 decagrams
1 kilogram is 10 hectograms
Hertz is the unit of frequency. The symbol for Herz is Hz. One hertz is
one cycle a second. The light beam behind your computer screen must pass
over the whole screen at least sixty times a second if the screen is not to
flicker. The is described as a refresh rate of 60 Hz. The speed of computer
processors is measured in megahertz. A megahertz is one million
cycles per second. The symbol for megahertz is MHz.
The size of computer files and the storage capacity of a computer disk is
measured in bytes. One byte is enough space to store one letter or
character. If the naming conventions for the metric system were followed, a
kilobyte would be one thousand bytes, just as a
kilometre is a thousand
meters and a
kilogram is a thousand grams.
Roughly, this is true. However, because the basic working of a computer is
in twos (the binary system) instead of tens (the metric system) many people
thought it would be good to have byte measurements in convenient numbers
from the binary system. They make a kilobyte one thousand and 24
bytes because that is two multiplied by itself ten times (two to the power
of ten). Both systems are in use.
1 kilobyte is one thousand bytes, or 1,024 bytes
Temperature
How hot or cold something is is measured in relation to two points: The
point at which a substance changes from a solid to liquid, or liquid to
solid, state - freezing point - and the point at which a substance changes
from a liquid to a vapour, or vapour to liquid, state - boiling point.
Different substances change at different heats, so a common substance is
used as the base: water.
The celsius (previously called centigrade) scale is a decimal
scale. It calls the freezing point of pure water 0 degrees and the
boiling point 100 degrees
The Réaumur scale is no longer used, but was once very popular in
France and Germany. This calls boiling point 80 degrees
Engels, writing in 1845 for Germans, explained that social
laws
could be as
certain as natural laws by arguing that
Andrew Roberts likes to hear from users:
Hertz and Megahertz
Megabyte and Gigabyte
1 megabyte is one million bytes, or 1,048,576 bytes
1 gigabyte is one thousand million bytes, or 1,073,741,824 bytes
"If the influences
demoralising to the working-man act more powerfully, more
concentratedly than usual, he becomes an offender as certainly as water
abandons the fluid for the vaporous state at 80 degrees, Réaumur."
Study
links outside this site
Andrew Roberts' web Study Guide
Picture introduction to this site
Top of
Page
Take a Break - Read a Poem
Click coloured words to go where you want
To contact him, please
use the Communication
Form
Maths index
*******************
cent = hundredth
centigram
centilitre
centimetre
deca = ten times
decagram
decalitre
decametre
deci = tenth
decigram
decilitre
decimetre
giga (giant)
= 1,000 million
Gigabyte
hecto = 100 times
hectogram
hectolitre
hectometre
kilo = 1,000 times
kilobyte
kilogram
kilolitre
kilometre
mega (great)
= million
Megabyte
Megahertz
metric = using ten
Metric
milli = thousandth
milligram
millilitre
millimetre
