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SI UnitsSI Units
OK, I really meant measuring OK, I really meant measuring things using the metric things using the metric
system. Used all over the system. Used all over the world except the US world except the US
Système International d‘Unités
SI BasicsSI Basics
• Le Systeme Le Systeme international international d'Unites officially d'Unites officially came into being in came into being in October 1960 and October 1960 and has been officially has been officially recognized and recognized and adopted by nearly adopted by nearly all countries. It is all countries. It is based upon 7 based upon 7 principal units:principal units:
• Type – Type – UnitUnit – Abbreviation – Abbreviation
• Length - Length - metremetre - m - m
• Mass - Mass - kilogramkilogram - kg - kg
• Time - Time - secondsecond - s - s
• Electric current - Electric current - ampereampere - A - A
• Temperature - Temperature - kelvinkelvin - K - K
• Amount of substance - Amount of substance - molemole - - mol mol
• Luminous intensity - Luminous intensity - candelacandela - cd - cd
But Where did it all come But Where did it all come from?from?• They felt that it had to be based in real They felt that it had to be based in real
things scientists and others could relate things scientists and others could relate to – things like Water, the Earth, to – things like Water, the Earth, candles, and things getting hotter.candles, and things getting hotter.
• Believe it or not – SI tries to keep it Believe it or not – SI tries to keep it simple.simple.
• And all based in Powers of Ten. And all based in Powers of Ten. (video) ((video) (http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/ ) )
It’s all about Water – HIt’s all about Water – H22O O & &
the Size of the Earththe Size of the Earth• It all started with figuring out the It all started with figuring out the
distance between the equator and the distance between the equator and the North Pole, then dividing that by North Pole, then dividing that by 10,000,000! That became a meter. 10,000,000! That became a meter. – OK – it was OK – it was supposedsupposed to be a meter, later to be a meter, later
they obtained better measurements of they obtained better measurements of the Earth’s size, and instead of changing the Earth’s size, and instead of changing the Meter, just made the it a standard the Meter, just made the it a standard size.size.
– A meter is also a convenient size for A meter is also a convenient size for human measurement.human measurement.
Length to Volume & Mass Length to Volume & Mass
• Once you had a Once you had a MetreMetre, you could , you could subdivide that into 10 units – decimeters.subdivide that into 10 units – decimeters.
• You could cube that to make a cubic You could cube that to make a cubic decimeter, also called a decimeter, also called a LiterLiter..
• Fill a Liter with water and it’s mass is 1 Fill a Liter with water and it’s mass is 1 KilogramKilogram..
Meter or MetreMeter or Metre
•OK – the official unit is the OK – the official unit is the Metre – and that goes back to Metre – and that goes back to the French.the French.
•We usually call it a Meter – We usually call it a Meter – the English versionthe English version
The Basics - againThe Basics - again
• metre [m]metre [m] – The metre is the basic unit of length. It is the distance light travels, in a vacuum, in The metre is the basic unit of length. It is the distance light travels, in a vacuum, in
1/2997924581/299792458thth of a second. of a second. • kilogram [kg]kilogram [kg]
– The kilogram is the basic unit of mass. It is the mass of an international prototype in the form The kilogram is the basic unit of mass. It is the mass of an international prototype in the form of a platinum-iridium cylinder kept at Sevres in France. of a platinum-iridium cylinder kept at Sevres in France. It is now the only basic unit still defined It is now the only basic unit still defined in terms of a material object, and also the only one with a prefix[kilo] already in place.in terms of a material object, and also the only one with a prefix[kilo] already in place.
• second [s]second [s] – The second is the basic unit of time. It is the length of time taken for 9192631770 periods of The second is the basic unit of time. It is the length of time taken for 9192631770 periods of
vibration of the caesium-133 atom to occur. vibration of the caesium-133 atom to occur. • ampere [A]ampere [A]
– The ampere is the basic unit of electric current. It is that current which produces a specified The ampere is the basic unit of electric current. It is that current which produces a specified force between two parallel wires which are 1 metre apart in a vacuum.force between two parallel wires which are 1 metre apart in a vacuum. It is named after the It is named after the French physicist Andre Ampere (1775-1836).French physicist Andre Ampere (1775-1836).
• kelvin [K]kelvin [K] – The kelvin is the basic unit of temperature. It is 1/273The kelvin is the basic unit of temperature. It is 1/273..1616thth of the thermodynamic temperature of the thermodynamic temperature
of the triple point of water.of the triple point of water. It is named after the Scottish mathematician and physicist William It is named after the Scottish mathematician and physicist William Thomson 1st Lord Kelvin (1824-1907).Thomson 1st Lord Kelvin (1824-1907).
• mole [mol]mole [mol] – The mole is the basic unit of substance. It is the amount of substance that contains as many The mole is the basic unit of substance. It is the amount of substance that contains as many
elementary units as there are atoms in 0elementary units as there are atoms in 0..012 kg of carbon-12. 012 kg of carbon-12. • candela [cd]candela [cd]
– The candela is the basic unit of luminous intensity. It is the intensity of a source of light of a The candela is the basic unit of luminous intensity. It is the intensity of a source of light of a specified frequency, which gives a specified amount of power in a given direction. specified frequency, which gives a specified amount of power in a given direction.
PrefixesPrefixes• yottayotta [Y] 1 000 000 000 000 000 000 000 000 = [Y] 1 000 000 000 000 000 000 000 000 =
10^24 10^24 • zettazetta [Z] 1 000 000 000 000 000 000 000 = 10^21 [Z] 1 000 000 000 000 000 000 000 = 10^21 • exa [E] 1 000 000 000 000 000 000 = 10^18 exa [E] 1 000 000 000 000 000 000 = 10^18 • peta [P] 1 000 000 000 000 000 = 10^15 peta [P] 1 000 000 000 000 000 = 10^15 • tera [T] 1 000 000 000 000 = 10^12 tera [T] 1 000 000 000 000 = 10^12 • giga [G] 1 000 000 000 = 10^9 giga [G] 1 000 000 000 = 10^9 (a billion)(a billion)• mega [M] 1 000 000 = 10^6 mega [M] 1 000 000 = 10^6 (a million)(a million) • kilo [k] 1 000 = 10^3 kilo [k] 1 000 = 10^3 (a thousand)(a thousand) • hecto [h] 100 = 10^2 hecto [h] 100 = 10^2 (a hundred)(a hundred) • deca [da]10 = 10^1 deca [da]10 = 10^1 (ten)(ten) • 1 = 10^01 = 10^0• deci [d] 0.1 = 10^-1 deci [d] 0.1 = 10^-1 (a tenth)(a tenth) • centi [c] 0.01 = 10^-2 centi [c] 0.01 = 10^-2 (a hundredth)(a hundredth) • milli [m] 0.001 = 10^-3 milli [m] 0.001 = 10^-3 (a thousandth)(a thousandth) • micro [µ] 0.000 001 = 10^-6 micro [µ] 0.000 001 = 10^-6 (a millionth)(a millionth) • nano [n] 0.000 000 001 = 10^-9 nano [n] 0.000 000 001 = 10^-9 (a billionth)(a billionth) • pico [p] 0.000 000 000 001 = 10^-12 pico [p] 0.000 000 000 001 = 10^-12 • femto [f] 0.000 000 000 000 001 = 10^-15 femto [f] 0.000 000 000 000 001 = 10^-15 • atto [a] 0.000 000 000 000 000 001 = 10^-18 atto [a] 0.000 000 000 000 000 001 = 10^-18 • zepto [z] 0.000 000 000 000 000 000 001 = 10^-21 zepto [z] 0.000 000 000 000 000 000 001 = 10^-21 • yocto [y] 0.000 000 000 000 000 000 000 001 = 10^-yocto [y] 0.000 000 000 000 000 000 000 001 = 10^-
2424
UsefulUseful Prefixes Prefixes
• giga giga [G] [G] 1 000 000 000 = 10^9 1 000 000 000 = 10^9 (a billion)(a billion)• mega mega [M] [M] 1 000 000 = 10^6 1 000 000 = 10^6 (a million)(a million) • kilo kilo [k] [k] 1 000 = 10^3 1 000 = 10^3 (a thousand)(a thousand) • hecto hecto [h] [h] 100 = 10^2 100 = 10^2 (a hundred)(a hundred) • deca deca [da][da] 10 = 10^1 10 = 10^1 (ten)(ten) • 1 = 10^01 = 10^0• deci deci [d] [d] 0.1 = 10^-1 0.1 = 10^-1 (a tenth)(a tenth) • centi centi [c] [c] 0.01 = 10^-2 0.01 = 10^-2 (a hundredth)(a hundredth) • milli milli [m] [m] 0.001 = 10^-3 0.001 = 10^-3 (a thousandth)(a thousandth) • micro micro [µ] [µ] 0.000 001 = 10^-6 0.000 001 = 10^-6 (a (a
millionth)millionth) • nano nano [n] [n] 0.000 000 001 = 10^-9 0.000 000 001 = 10^-9 (a (a
billionth)billionth)
Lets get Real - LengthLets get Real - Length
• What units do we really use for What units do we really use for length? And how big are they?length? And how big are they?– KilometersKilometers– MetersMeters– CentimetersCentimeters– MillimetersMillimeters– Micrometers – MicronsMicrometers – Microns– Ångström - angstromÅngström - angstrom
Getting Real - MassGetting Real - Mass
• Mass is Not Weight!!!!Mass is Not Weight!!!!
• What units do we really use for What units do we really use for mass? How much is that really?mass? How much is that really?– kilogramkilogram– gramgram– milligrammilligram– microgrammicrogram
Mass is Not Weight? WHAT?Mass is Not Weight? WHAT?
• Weight is the force of attraction Weight is the force of attraction between two objects.between two objects.– Your weight is the force of attraction Your weight is the force of attraction
between you and the Earthbetween you and the Earth
• Mass is the amount of material Mass is the amount of material (electrons, protons and neutrons) in a (electrons, protons and neutrons) in a substance. The amount of “stuff”. It substance. The amount of “stuff”. It provides a gravitational attraction and provides a gravitational attraction and has inertia.has inertia.
Mass and Weight againMass and Weight again
• Your mass doesn’t change! (unless)Your mass doesn’t change! (unless)
• Your weight changes, depending on Your weight changes, depending on where you are:where you are:– On the moon – 1/6On the moon – 1/6– On Mars – 1/3On Mars – 1/3– On Jupiter – 2.5xOn Jupiter – 2.5x– In orbit - 0In orbit - 0
Weighing the Earth 1Weighing the Earth 1
• First – weigh yourself on a bathroom First – weigh yourself on a bathroom scalescale
Weighing the Earth 2Weighing the Earth 2
• Now take the scale out to the curb of Now take the scale out to the curb of the roadthe road
Weighing the Earth 3Weighing the Earth 3
Getting real with VolumeGetting real with Volume
• Volume, the amount of Space things Volume, the amount of Space things take up – is a “cubic” measurement – l take up – is a “cubic” measurement – l x w x hx w x h
• We use two systems for Volume which We use two systems for Volume which are really the same are really the same
• 1 liter = 1000 ml = 1000 cm1 liter = 1000 ml = 1000 cm33
• 1 milliliter = 1 cm1 milliliter = 1 cm33
• Occasionally we might use cubic Occasionally we might use cubic meters mmeters m33 or cubic kilometers km or cubic kilometers km33..
VolumeVolume
• How much is that really?How much is that really?
• LiterLiter
• MilliliterMilliliter
Measurement ActivityMeasurement Activity
• Measure the following objects in m, cm, Measure the following objects in m, cm, mm:mm:– Your desk (l & w & h)Your desk (l & w & h)– The doorThe door– Your height, your nose to finger tip, your foot, Your height, your nose to finger tip, your foot,
your “shaka”, the room.your “shaka”, the room.
• To convert m<->cm<->mmTo convert m<->cm<->mm– 1000 mm = 100 cm = 1 m1000 mm = 100 cm = 1 m– 10 mm = 1 cm10 mm = 1 cm– cm to mm: x10 mm to cm: cm to mm: x10 mm to cm: ÷÷1010
m to cm: x100 cm to m: ÷ 100m to cm: x100 cm to m: ÷ 100m to mm: x1000 mm to m: ÷ 1000m to mm: x1000 mm to m: ÷ 1000
ObjectObject MeterMeter CentimetCentimeterer
MillimeteMillimeterr
Desk – LDesk – L
Desk – WDesk – W
Desk – HDesk – H
Door – HDoor – H
Door – WDoor – W
Room – LRoom – L
Room – WRoom – W
Your HeightYour Height
Nose to Nose to fingerfinger
FootFoot
ShakaShaka
•۰۱۲۳۴۵۰۱۲۳۴۵٦٧٨٩٦٧٨٩
DisclaimerDisclaimerAlohaAloha
I put together these power points for I put together these power points for use in my science classes.use in my science classes.You may use them in your classes.You may use them in your classes.
Some images are public domain, Some images are public domain, some are used under the fair-use some are used under the fair-use provisions of the copyright law, some provisions of the copyright law, some are mine. Copyright is retained by are mine. Copyright is retained by the owners!the owners!
Ted BrattstromTed Brattstrom
