# Scientific Measurements

## Presentation on theme: "Scientific Measurements"— Presentation transcript:

Scientific Measurements

Scientific Measurements
Measurement: a means of describing observations using numbers and a UNIT of measure (ex: 11 inches) - makes a comparison with a known standard - ALL measurements contain at least one of the four basic dimensional quantities (length, mass, time, temperature) Systems of measurement: 1) Metric System (aka International System of Units (SI) 2) English System * See handout reference)

Basic Measurement Units
Unit Metric English Instrument Time: instant something happens OR period of change Length: distance between 2 points Mass: amount of matter in an object Temperature: measurement of how hot or cold something is (average KE = average Kinetic Energy) Second (s), minute (min), hour (hr), year (yr) Meter (m), centimeter (cm), millimeter (mm), kilometer (km) Gram (g), kilogram (kg) Celsius (0C) Kelvin (0K) Clock, stopwatch, sundial, hour glass Same as Metric Mile (mi), yard (yd), foot (ft), inch (in) Meter stick, yardstick, ruler, tape measure Ounce (oz), pound (lb), ton (t) Balance, scale Fahrenheit (0F) Thermometer

Derived Units Examples of Derived Units: Volume; Density
** Some properties are best described by using some mathematical combination of the basic quantities. These mathematical combination of basic quantities are referred to as DERIVED UNITS. Examples of Derived Units: Volume; Density Volume: amount of space an object takes up Density: amount of material contained in a space Regular Shape: Volume L . W . H cm . cm . cm = cm3 Density mass (g) volume (cm3) Irregular Shape: displacement method (1 ml = 1 cm3) Drop object in known volume of water and record the difference Density = mass (g) volume (cm3)

Let’s measure some irregular shapes!
What is the volume of the dinosaur in ml? 0.8 ml

Working With Numbers Every number has a decimal version (4 = 4.0)
Rounding off numbers: most of the time to the nearest 10th or 100th Every number has a decimal version (4 = 4.0) Rules: you always check the number to the right to decide > 5 Ex: < 4 Leave it alone thousandths tenths hundredths (5.363) (5.4) (5.36) The “rules” Five or more, raise the score Four or less, leave it rest

Rounding Practice Time
Working With Numbers Rounding Practice Time Round to the nearest tenths place: 3.73= 2. 65= 4.324= 18.957= = Round to the nearest Hundredths place: 6.546= 16.342= = 12.997= = 3.7 6.55 2.7 16.34 4.3 124.86 19.0 13.00 2345.6

Converting numbers percents (%)
Number % - move the decimal point to the right 2 places and add % sign (** multiply by 100 = same thing) 54% 0.54= % Number - move the decimal point to the left 2 places and lose % sign (** divide by 100 = same thing) 47%= 0.47

Converting numbers percents (%)
Numbers / Percents Practice Time Convert the following percents to numbers: 75%= 83%= 58.8%= 73.94%= Convert the following numbers to percents: 0.76= 0.43= 0.435= 0.683= 0.75 76% 0.83 43% 43.5% 0.588 0.7394 68.3%

Scientific Notation (aka math shorthand)
Takes very large & very small numbers and makes them shorter. HOW? Move the decimal point until there is only one number to the left of the decimal point and count the numbers – this is the EXPONENT If you need to count to the RIGHT to get back to the original number then the EXPONENT is POSITIVE. If you need to count to the LEFT to get back to the original number then the EXPONENT is NEGATIVE. Example: 1,750, x x 10-5 Positive # See pg. 1 of ESRTs Negative #

Sci Notation Practice Time
Move the decimal point until there is only one number to the left of the decimal point and count the spaces – this is the EXPONENT Practice: ** do these on your own, then we’ll check them 76,000 = = 130 = = 7.6 x x x x 10-2 8.4 x 103 = 1.2 x 10-4 = 5.5 x 10-5 = x 107 = 8, ,504,000

Unit Conversions X = 65.6 miles
1) Set up the problem; KNOW the conversion factor 2) Make into a fraction and multiply by what you know (set up the conversion factor in order to cancel units) Example: 1) 105 km = how many miles? 2) 105 km mi km X Conversion factor Unwanted units cancel 3) = 65.6 miles

Unit Conversions Ctd X = 96 km
1) Set up the problem; KNOW the conversion factor 2) Make into a fraction and multiply by what you know (set up the conversion factor in order to cancel units) Example: 1) 60 miles = how many km? 2) 60 mi km mi X Conversion factor Unwanted units cancel 3) 60 x 1.6 = 96 km

Who wants more practice : Try, “Working With Numbers worksheet”
Rounding Percents Scientific notation Unit Conversions Try, “Working With Numbers worksheet”