The Major Tool of Science, that of Measurements

The process of obtaining numerical values representing physical properties is called measurement. These properties include such things as length, mass, or time, by way of a unit of measurement. A unit of measurement is a magnitude representing a physical quantity by use of a standard for measurement of that physical quantity. A measuring device is a piece of equipment used to measure a physical quantity based on a standard for measurement.

 Measurement and Objectivity

Measurement is the most objective part of science since the resulting numbers are what they are. Using mechanical devices for measurement improves objectivity by removing human subjectivity. The validity of a measurement is only as valid as the theory behind it.

Units of Measure in Physics

Numerical values given physical quantities relative to some standard are called unites of measure. The global standard system of measurement units is called the International System of Units or SI units for sjort.

Seven SI Base Units
meter	distance
kilogram	mass
second	time
ampere	current
kelvin	temperature
mole	amount of substance
candela	intensity of light

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Common Derived SI Units
newton	force		coulomb	charge
Joule	energy		volt	potential
tesla	flux density		farad	capacitance
hertz	frequency		ohm	resistance

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SI unit prefixes
Prefix	10n	Scale	Decimal
yotta- zetta- exa- peta- tera- giga- mega- kilo- hecto- deca- none deci- centi- milli- micro- nano- pico- femto- antto- zepto- yocto- 10 24 21 18 15 12 9 6 3 2 1 0 -1 -2 -3 -6 -9 -12 -15 -18 -21 -24    Septillion Sextillion Quintillion Quadrillion Trillion Billion Million Thousand Hundred Ten One Tenth Hundredth Thousandth Millionth Billionth Trillionth Quadrillionth Quintillionth Sextillionth Septillionth    1,000,000,000,000,000,000,000,000 1,000,000,000,000,000,000,000 1,000,000,000,000,000,000 1,000,000,000,000,000 1,000,000,000,000 1,000,000,000 1,000,000 1,000 100 10 1 0,01 0,01 0,001 0,000,001 0,000,000,001 0,000,000,000,001 0,000,000,000,000,001 0,000,000,000,000,000,001 0,000,000,000,000,000,000,001 0,000,000,000,000,000,000,000,001

As a result 1,000 meters is a kilometer, a hundredth of a meter is centimeter and a thousandth of a meter is a millimeter.