The International System of UnitsAlso known as SI unitsIt is the modern day metric systemIt is a form of measurement used all around

the world

When was SI created?The system of measurement was created in

1960 after the General Conference on Weights and Measures asked the International Committee for Weights and Measures to conduct a study on international measurements.

In 1954, they created six base units:Meter, kilogram, second, ampere, Kelvin, and candela

When was SI created? (cont.)In 1960, they created the name

International System of Units, abbreviated SI, from the French name: Le Systeme international d’unites.

They added ONE more SI unit (mole) in 1971

SI units, Symbols and QuantityName Symbol Quantity

Meter m Length

Kilogram kg Mass

Second s Time

Ampere A Electric Current

Kelvin K Thermodynamic temperature

Mole mol Amount of substance

Candela cd Luminous intensity

The Metric SystemA system of measurement based on the

number “10”

Records show it was used in the mid 1500’s

Used ALL over the world as the main system of measurement, EXCEPT in these countries:LiberiaBurmaThe United States

PrefixesPrefix Symbol Meaning

Kilo- k 1,000

Hecto- h 100

Deka- da 10

Unit Just the unit 1

Deci- d 0.1 (one tenth)

Centi- c 0.01 (one hundredth)

Milli- m 0.001 (one thousandth)

LengthDefinition- the distance from one point to

another

Basic SI Unit- meter (m)

Tools to measure length- metric ruler (centimeters)Meter stick (100 centimeters)

MassDefinition- the measure of the amount of

matter in an object.

Basic SI Unit- kilogram (k)

Tools to measure mass:ScaleTriple Balance Beam

Difference between Mass and Weight

Mass- the amount of matter in an object

Weight- a measure of the force of gravity acting on an object. It is measured using a scale.

You mass is the same, no matter where you go. Your weight changes due to gravity.Ex: You weigh 100 lbs on Earth. If you went to

the moon, you would weigh 16.6 lbs.

VolumeDefinition- the amount of space an object takes

up.

Basic SI Unit- Liter (L)

Tools to Measure Volume:Volume of a Liquid- graduated cylinder (L)Volume of Rectangular Solids-

Length x Width x Height (cm3)Volume of Irregular Solids- Water displacement

DensityDefinition- a measure of how much mass is

contained in a given volume.

Units- g/cm3 or g/mL

Calculate- Density= Mass/ Volume

TimeDefinition-

Basic SI Units- second (s)

Tools for measure time-ClocksWatches

TemperatureDefinition- How warm or cold something is

Basic Units of SI- Kelvin (K)Scientists use Celsius (C)

Tools to Measure Temperature- Thermometer

Conversion between UnitsHow do you convert Meters to Centimeters?

1. Write down the number you want to convert and its proper unit. Ex: 100 meters = ? cm

2. If the number is a whole number, add the decimal point at the end of the number. Ex: 100. meters

2. Using the conversion chart, move the decimal point towards the proper unit.

Conversion Chart