Measuring With Scientific Units

Measuring With Scientific Units

MEASUREMENT • TAKE OUT YOUR HOMEWORK • Check your Procedure to see if you have measurements FOR EVERYTHING. • BEGIN WORKING ON METRIC MANIA

MEASUREMENT • MEASUREMENT • Measurement is in NUMBERS and UNITS. • Most of the world uses the METRIC SYSTEM • Based on the ‘NUMBER TEN’ • Based on the METER

1.3 Measurement International System of Units (SI) MEASUREMENTS ALWAYS HAVE A NUMBER AND A UNIT 4m, 25s, examples?????? Allow scientists from all over the world to understand one another’s measurements

MEASUREMENT: SYMBOLS

1.3 Measurement

MEASUREMENT: UNITS LENGTH METER: measures distance VOLUME LITER: Volume = length x width x height = cm3 or mL

MEASUREMENT: UNITS WEIGHT AND MASS GRAM: mass & weight • WEIGHT depends on WHERE YOU ARE IN THE UNIVERSE • Changes depend on GRAVITY • Mass depends onTHE NUMBER AND TYPE OF ATOMS • ALWAYS STAYS THE SAME

MEASUREMENT: UNITS • TEMPERATURE AND TIME CELSIUS: temperature • TEMPERATURE measures AMOUNT OF HEAT • WHAT IS YOUR BODY TEMPERATURE? • 98.6 ⁰F • 37 ⁰C SECONDS: time • TIME measures ORDER OF EVENTS

MEASUREMENT: UNITS DENSITY • GRAMS PER VOLUME: density • Density = amount of MASS per unit of VOLUME = grams / milliliter = grams / cubic centimeter = MASS ÷ VOLUME PURE WATER = 1g / mL LEAD = 11g / mL

1.3 Measurement - PREFIXES

CONVERSIONS Conversions are easy because they’re BASED ON THE NUMBER TEN • Just MOVE THE DECIMAL! Setting up the Divisions k  h  D base d  c  m 1,000 units 100 units 10 units 1 unit 1/10 unit 1/100 unit 1/1,000 unit

CONVERSIONS k  h  D base d  c  m 1,000 units 100 units 10 units 1 unit 1/10 unit 1/100 unit 1/1,000 unit • If you’re going from SMALL amounts to LARGE amounts, move the decimal TO THE LEFT • 300 centimeters = 3.00 meter • 56 liters = ______ kiloliters? • .056 kL • 82.3 milligrams = _______ decigrams? • .823 dg

CONVERSIONS k  h  D base d  c  m 1,000 units 100 units 10 units 1 unit 1/10 unit 1/100 unit 1/1,000 unit • If you’re going from LARGE amounts to SMALL amounts, move the decimal TO THE RIGHT • 95 grams = 95,000 milligrams • 20.5 decameters = _________ meters? • 205 m • 6.82 liters = .0682 cL centiliters? • 682 cL

CONVERSION FACTORS • Converting from one unit to another • You can also use a CONVERSION FACTOR: a ratio that is equal to ONE and is used to convert from one unit to another • Convert 1gram to milligrams: • 1g x 1,000mg/1g = 1,000mg • Convert 10meters to kilometers • 10m x 1km/1,000m = 0.010km

REVIEW: LENGTH • METER: distance • Divisions km  hm  Dm  m  dm  cm  mm 1,000 100 10 1 1/10 1/100 1/1,000 Using your meter stick, show one meter, one decimeter, one centimeter, and one millimeter

REVIEW: VOLUME Volume = length x width x height = cm3 or milliliters • Using your graduated cylinder, show one milliliter, one centiliter, AND one deciliter

DENSITY • Compare the density of the same sized objects on your desk.

1.3 Measurement Measurements in science are DATA. It is important that they are both accurate and precise.

1.3 Measurement Precision vs. Accuracy Precision = exactness (more significant digits: 1.256m stride, not 1m) Accuracy = closeness to actual value. (using a quartz or atomic watch instead of counting in your head) try it.

1.3 Measurement SCIENTIFIC NOTATION A way of expressing a value by powers of 10. Make very large and very small numbers easier to work with. 300,000,000 = 3.0 x 108 .0000000088 = 8.8 x 10-9

For practice, write these numbers out in long form.

Measuring With Scientific Units