2. Ch. 2 – Scientific Method  A systematic approach to solve problems through investigations by 1. Observing, 2. Generalizing, 3. Theorizing, 4. Testing, 5. Conclusion.  What’s done in an observation  Collect data, communicate  Generalizing  Organize data, hypothesis  Theorizing  Planning and predicting

3. TTest DDesign experiment, test, graph and interpret results CConclusion MMay change hypothesis and retest EExplain what happened in your results

4. Measurements  Why do we need measurements?  If I told you to go get me a pop would you know what size?  The International System of Units (SI) is used throughout the world so we don’t confuse figures and measurements.  SI is metric  Written the following way: 21 400 or 0.157 82  7 SI fundamental units  Mass, time, temperature, length, amount of substance. Pg. 34

5. SI Unit Prefixes  Unit of measurements for length  KHDMDCM  Kilo, hecto, deka, meter, deci, centi, milli  Ex. Kilogram (1000 grams) or Kilometer (1000 meters)  1 gram is about 1 pencil mass  Your book is about 2 Kg  Derived Unit – are combinations of fundamental units.

6. Derived Units  Area  length X width (m 2 )  Volume  length X width X height (m 3 )  Volume is the amount of space occupied by an object.  1ml = 1cm 3  1 liter = 1000-ml  1 ml = how many liters?  Density is mass divided by volume (D=m/v)  How heavy something is for its size.  Ex. Pg. 38 (Density Lab)

7.  Temperature is the measure of the average kinetic energy of the particles in a sample of matter.  What is the SI unit for temp.?  Kelvin (K)  Heat is the sum of the kinetic energy of the particles in a sample of matter.  How does a thermometer work?  We use Celsius more than Kelvin  0 C = 273 K – freezing point  100 C = 373 K- boiling point

8.  Joule is force times length (f X l)  1 J = 1 n-m  Joule is the SI unit for energy  A calorie is the amount of heat needed to raise the temperature of 1 g water 1 degrees C.  1 calorie = 4.184 J  Kcal or C = KJ  Food Calories are kilocalories.  Conversion Factors – Sample Problem 2-2

9. SSpecific heat is the amount of heat energy required to raise the temp. of 1 g of a substance 1 degree C. LLabel is J/(g x C) WWater heats up and cools down slowly, thus it has a high specific heat. AAccuracy vs. Precision AAccuracy is determined by how close your results are to the correct answer. PPrecision is determined by how close your results are to each other. EEx. Dart Board – pg. 44 SSample Problem 2-3 (Percent Error)

10. SIGNIFICANT FIGURES  Significant figures are all the digits known with certainty plus one final digit, which is uncertain or estimated.  Read pg. 46 – bottom 2 paragraphs  Read pg. 47 – Table 2-5  Do Sample Problems on pg. 47 & 48  Rounding off Addition & Subtraction Problems  Rounding off Multiplication & Division Problems

11. Scientific Notation  This is very helpful to determine the correct number of significant figures.  Ex. 50 890  5.089 X 10 4  Ex. 0.005031  5.031 X 10 -3  Ex. 74 621 000  7.462 1 X 10 7  Using Adding & Subtracting Scientific Notation  Using Multiplying & Dividing Scientific Notation