Chapter

 Observation – using the senses to gather information about the natural world  Science dependent on keeping records of observations and interpreting them  Without them, no interpretation or conclusions

ItemObservation 1 2 3

Observations at Scene 1.Blood type = B 2.Fiber sample = polyester 3.Powder found – white 4.Shoe print found = work boot Suspect 1: 180 lb male Blood type = B Sweater = polyester Works in sugar factory Suspect 2: 220 lb male Blood type = B Blazer = wool knit Pastry chef Suspect 3: 120 lb female Would not comply Pants = polyester Automobile sales woman

 Quantitative observations – involve measurements that yield meaningful, numerical results  Qualitative observations – yield descriptive, nonnumerical results  Qualitative vague, quantitative more useful due to numbers and units  E.g. height comparison

 Pick out the quantitative and qualitative observations from each phrase.  grams of NaCl dissolve in 10 milliliters of H 2 O to produce a clear solution.  2. The spider on the wall has only seven legs remaining but is still big and hairy.  3. When 0.50 milliliter of a solution is put into a flame, the flame turns a brilliant green.

 Systems of measurement developed from ancient times to make communication and commerce easier  Standards established to make measurements reproducible and consistent  Metric system – international decimal-based system of measurement  Conversions made with factors of 10  Base units for reference

Common Prefixes Pico p Nano10 -9 n Micro10 -6  Milli10 -3 m Centi10 -2 c Deci10 -1 d kilo10 3 k

 International System of Units (SI) – main system of measurement used in science  Internationally agreed upon since 1960s  Based on physical standards  Described by stable properties in universe

 Mass and weight often used interchangeably, but not same thing  Mass – measure of amount of matter  Same value everywhere in universe  Weight – force of attraction between object and Earth  Changes with respect to location  Base unit of mass in SI is kilogram  Standard held in Paris, France

 Length – measurement of anything from end to end  SI unit meter  Set in 1889 by International Bureau of Standards  Volume – amount of space an object takes up  Derived unit – based on another unit  SI unit cubic meter

 Heat and temperature not the same  Temperature – average kinetic energy of particles in a material; thermal energy  Heat – movement of thermal energy from warmer object to cooler object  Measured with thermometer – one of earliest developed by Galileo  Thermometers based on principle of thermal expansion

 Three temperature scales based on different standards  Fahrenheit – based on human body temperature; freeze 32, boil 212  Celsius – based on water temperature; freeze 0, boil 100  Kelvin – limit to how cold things can get, no limit to how hot things can get; zero at absolute zero ( degrees C)  Converted by adding to Celsius readings

 SI unit for time = second  Originally defined as fraction of time required for Earth to orbit Sun  Current definition much more complicated