Units Of Measurement

Measurement Quantitative data (represents quantities) Quantity: something that has magnitude, size or amount Example: a box has a quantity that is represented by volume A track has a quantity that is represented by meters or miles

SI Measurement International Standards of Measurement There are 7 SI Base Units

SI Base Units QUANTITY SYMBOL BASE UNIT NAME & Symbol length l Meter (m) Mass m Kilogram (kg) Time t Seconds (s) Temperature T Kelvin (K) Amount of Substance n Mole (mol) Electric Current I Ampere (A) Luminous intensity Iv Candela (cd)

REMEMBER Meters = m Liters = L Grams = g Seconds = s

SI Base Units (Common) Mass: the quantity that measures how much matter Base: gram Weight: A measure of gravitational pull on matter Length: the quantity that measures distance Base: meter,

SI Prefixes Each Base Unit can carry with it a number of prefixes Each prefix represents a quantity larger or smaller than the Base Unit There are 8 prefixes you need to learn

SI Prefixes

SI Prefixes You will be asked to convert from one unit to another The largest numbers are at the top of the chart (mega), the smallest numbers are at the bottom of the chart (micro)

SI Prefixes When you move UP the chart from a smaller number to a larger number MOVE THE DECIMAL TO THE LEFT When you are moving DOWN the chart from a large number to a smaller number MOVE THE DECIMAL TO THE RIGHT

Lets try It !!! 2300 kilometers = 230000 dekameters 2300 kilometers to dekameters Decide which way to move your decimal (Move right) Next count how many unit difference it is from kilo to deka 2 2300 kilometers = 230000 dekameters

Practice these next few conversions! 3.25 micrograms --> dekagrams .00562 kiloliters --> gigaliters 33.25 centimeters --> hectometers 650 meters --> millimeters 68520 picoliters --> deciliters

Answers Decimal to left 7 places: .000000325 dekagrams Decimal to left 6 places: .00000000562 gigaliters Decimal to left 4 places: .003325 hectometers Decimal to the right 3 places: 650000 millimeters Decimal to left 11 places: .00000068520 deciliters

Derived Units Combination of units Ex: m2, g/mL, etc.

Volume Volume is a derived unit: Length x width x height Units: (m) x (m) x (m) = m3 (cubic meter) Or (cm) x (cm) x (cm) = cm3 (cubic centimeter)

Density Density is a derived unit: Density = mass / volume = “stuff”/”space” Units for density could be g/L, kg/m3 or g/cm3 Be sure you know which units you are using in your equation and be consistent in your answer

Density Wheel The wheel is a quick way to determine what you are solving for Using the wheel: 1.) Cover the variable that you are solving

2.) Determine the formula with the remaining variables. 3.) Multiply across in the wheel, Divide up and down in the wheel SHOW ALL OF YOUR WORK!

m : : d v x

Common Conversion Factors Used to convert between related measurements Some are common to you, some are new or often forgotten These conversions will be used in dimensional analysis to convert between units Ex: 1” = 2.54 cm

QUESTIONS?