Units of Measurement Science 9 September 2014

Vocab Unit – a standard of measurement in which other measurements are expressed. English System (United States Customary System) – system of measurement used in the US, includes inches, gallons, pounds, miles, etc. Metric System – system of measurement used in countries other than the US and by the scientific community; units are organized by factors of 10. Prefix – element placed at the beginning of a word that changes the meaning of the word; in the metric system, it indicates a unit smaller of larger than the basic unit by factors of 10.

Why is measurement important? Use it in daily life –Cooking –Construction –Decorating a room –Driving Communication –Need to be able to communicate measurements and distances to other people

Measurement & Physics Physicists try to find relationships between the quantities they measure  use units of measurement to do this Measure the very largest and smallest things in the universe –Smallest: mass of an electron = yg –Largest: light years (distances between stars and galaxies

Units of Measurement DistanceMassTimeArea/Vol ume Tempera ture inchmilligramhoursin^2, in^3 Fahrenheit meterouncessecondsm^2, m^3 Celsius milepoundsdaysLitersKelvin feetgrammonthsGallon centimeter kilogramyearsQuart millimeter tonsminutesPint

How to use a ruler: 1. Determine if you are measuring in centimeters or inches and find that unit’s side of the ruler. inches centimeters

How to use a ruler 2.Place the “0” mark at one end of the object you are measuring. “0” mark

How to Use a Ruler 3.Record the ruler marking that falls at the other end of the object For INCHES: - Each dash after a whole inch is 1/16 of an inch For CENTIMETERS: - Each dash after a whole centimeter is 1/10 of a centimeter

Measurement Lab

Relative Size UnitRelative SizeExamples Inches 1 inPhoto size, body parts Feet1 ft = 12 inHeight of people, room size Yard1 yd= 3 ftFootball field Meters1 m ~ 1 ydHeight of people, track length Kilometers1km = 1000mCar travels, between cities Centimeters1 cm = 0.01 mPaper, small machine parts, body parts Millimeters1 mm = mCoins

Two Main Systems of Measurement United States Customary System (USCS) System International (SI)- Metric System

USCS Used in the U.S. and Burma Distance: inch (in), foot (ft), yard (yd), mile (mi) Mass: pound (lb) Time: second (sec) Temperature: degrees Fahrenheit (  F)

Metric System Used by all other countries and the scientific community Units that are larger or smaller units than the basic units are defined in multiples of 10 Basic Units –Distance: meter (m) –Mass: gram (g) –Time: second (s) –Temperature: degrees Celsius –Volume: Litre (L)

Metric System: Prefixes Adding a prefix to a basic metric unit increases or decreases the unit size by a factor of 10 Prefixes are always added to the beginning of Metric basic units For example, –centimeter (cm) –milliliter (mm) –kilogram (kg)

Metric Prefixes PrefixSymbolRelation to Basic Unit milli-m1000 mm = 1 m centi-c100 cm = 1 m deci-d10 dm = 1 m deka-da1 dam = 10 m hecto-h1 hm = 100m kilo-k1 km = 1000 m

Common Unit Equivalencies 1 m = 100 cm 1 m = 1000 mm 1 km = 1000 m 1 ft. = 12 in. 1 yd. = 3 ft. 1 min = 60 s 1 hr = 60 min 1 day = 24 hr. 1 year = 365 days

Conversion Factors Each unit equivalency can be written as TWO conversion factors. To make the conversion factors, place one side of the unit equivalency on the top and the other on the bottom of a fraction bar. Then, flip the fraction to get the second conversion factor.