si units. why is it important to have standards? let’s say you go in the local footlocker with...
TRANSCRIPT
SI Units
Why is it important to have STANDARDS?
Let’s say you go in the local Footlocker with some cash, tell the salesman that you want these in a size 10.
So.. The salesman brings you back these instead… in size 10, of course. What happened?
Standards
It is important to have a set STANDARD for measurements, so that no matter where or what you are measuring, the measurement MEANS the same thing.
In 1960, international scientists agreed to standards of measurements for use in the scientific community – System International d’Unites – also known as, SI Units
SI Base Units
Quantity - TIMESymbol in equations - tUnit - secondAbbreviation - s
SI Base Units
Quantity - Length Symbol in Equations - l or d Units - meters Abbreviation - m
SI Base Units
Quantity - mass Symbol in equations - m Unit - kilogram Abbreviation - kg
SI Base Units
Quantity - Temperature Symbol in equations - T Unit - kelvins Abbreviation - K
Apia29° 24°
Bangkok31° 27°
Brisbane20° 11°
Buenos Aires15° 4° Cairo
37° 27° Dubai
38° 31° Johannesburg
26° 11° Los Angeles
21° 15° Melbourne
18° 7° Nadi
29° 22° New Delhi
34° 28° New York32° 22°
Nuku'alofa28° 18°
Rarotonga29° 19° Rome
29° 18° Scott Base-28° -32° Shanghai29° 26°
Singapore29° 25° Sydney17° 12° Tokyo
34° 28° Vladivostok
-68° -75°
Celsius Fahrenheit
ºF = 1.8(ºC) + 32For example, the weather report in Cairo today states that it is 30ºC. What type of
clothing should I wear?ºF = 1.8(30ºC) + 32
ºF = 54 + 32ºF = 86ºF
What about ºC ºF
Same equation ºF = 1.8(ºC) + 32, rearranged.
ºC = (ºF – 32)/1.8
While staying in Amsterdam, you decide to cook afternoon tea for your flat mates. You need to convert your
US recipe from 420º Fahrenheit to Celsius.
What about Kelvin, the SI Unit?
Once you know Celsius, Kelvin is EASY!
ºK = ºC + 273OR
ºC = ºK - 273
SI Base Units
Quantity - mole Symbol in equations - n Unit - mole Abbreviation - mol
Practice
What is the temperature in Farenheit and Kelvin at 0°C?
Prefixes
King Henry Died Monday Drinking Chocolate Milk
Kilo- Hecto- Deka- <Meters> Deci- Centi- Milli-
NEED TO KNOW
If I need to convert from meters to centimeters, this requires a two step movement of my decimal point.
K H D M D C M
0.0123 m = _1.23__ cm
Practice Conversions
23.2 km to m 65.001 cm to m 10000.2 mg to dag 123456789 dg to μg
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F
Homework
1. -273 _______ _______2. _____ _______ 212°F3. _____ 450 K _______4. _____ _______ 98.6°F5. _____ 294 K _______6. _____ _______ 77°F7. _____ 225 K _______8. -40°C _______ _______
Fill in the chart below.
°C K °F