Scientific Method A method by which natural phenomena are explained

How would you describe thunder & lightning?

A mythological being?

A dream?

Or science?

Scientific Method Rules of the Game u 1. One assumption: the phenomena to be described are able to be described by natural phenomena.

Steps of the Scientific Method u 1. Make observations on something interesting u 2. Form a hypothesis, an educated guess u 3. Perform experiments to disprove the hypothesis u 4. Reevaluate the hypothesis

Conducting an Experiment u Control group –a group in an experimental study that receives no special treatment u Experimental group –a group receiving special treatment in an experimental study

So what’s the difference between these two groups anyway? u Independent variable –a variable that is manipulated or modified in an experiment –CAUSE u Dependent variable –a variable in an experimental study that may change as a result of the manipulation of the independent variable –EFFECT

We’ve got to do what? Graph it?!?! u Independent variable –x axis u Dependent variable –y axis X Y

Once the reevaluation is over.. u Theory: a tested explanation of natural phenomena u Law: a concise statement or mathematical equation about a relationship, i.e. E=mc 2

Qualitative versus Quantitative

How would you describe this picture?

Possible ways to describe it: u Number of people u Number of decorations u Number of lights u Appearance of people u Type of decorations u Type of wall coverings

What does this mean? u Quantitative –a physical description involving the numbers of a situation u Qualitative –a physical description involving the physical appearance of a situation

While it may seem that these two are opposite, they are really the halves of the whole description.

Application to a Candle u What types of observations can we make about a candle? How about in order to describe how a candle is able to keep a flame and give off light?

Candle Activity

The Metric System

History: Early measurements reflected the size of the king or queen of the land

The problem was that as the king’s size changed so did the basis for measurement

In 1670, Gabriel Mouton devised a system of measurement based upon standards instead of the kings’ features The Metric System

Metric vs. English u easier to use since “nonexact” measurements are expressed as decimals, not fractions u easier to use since conversions are all based upon powers of 10

Metric Base Units

Metric Prefixes (Greater than)

Metric Prefixes (Less Than)

So how do we use this? u 1000 g = 1 kg u 100 m = 1 hm u.01 m = 1 cm u.001m = 1 mm

Metcetera (Wet to Dry Volume) u 1.0 cm 3 = 1.0 mL u 1.0 dm 3 = 1.0 L

Conversions u BiggerBase UnitSmaller u k, h, da m, l, gd, c, m

Convert u 5 dm to cm u 5 mm to cm

u 5 km to dam u 5 hm to km

2 step conversions u 5 km to mm u 4 cm to dam

Measurement Lab u Station 1: Using a ruler –Never measure from the end

Measurement Lab u Station 2: Using a graduated cylinder –Meniscus: the curved line of liquid that is read for measurement in certain types of glassware

Measurement Lab u Station 3: The Pipette u Using a known piece of glassware to calibrate an unknown piece of glassware

Measurement Lab u Station 4: Using different types of pipettes –Mohr and Volumetric

Measurement Lab u Station 5: Using the buret –Only glassware that is graduated upside down

Measurement Lab u Station 6: Using a thermometer

Measurement Lab u Station 7: Using a balance –How many digits do you write down?

Measurement Lab u Station 8: Using a barometer –Used to measure pressue –Units: mm Hg

Scientific Notation u Shorthand way of writing numbers without having to use placeholder zeros u 1,000,000 = 1 x 10 6 u = 5 x 10 -3

Scientific Notation u Rules: 1.The number in front of the decimal must be between 1 and 9. 2.In order to get only one number in front of the decimal you will need to move the decimal 1. If you move to the right, the exponent is negative 2. If you move to the left, the exponent is positive

Write these in scientific notation: u u 1,002,000,000 u 0.34 u 403

Write these in standard notation: u 2 x u 3 x 10 4 u 5.67 x u 4.56 x 10 2

Significant Digits u Numbers (digits) that show the degree of accuracy and precision of a measurement u Accuracy: How close a measurement is to the accepted value u Precision: Repeatability of a set of measurements to be similar in value

Atlantic-Pacific Rule u Atlantic: –If the decimal is absent, start counting from the right (Atlantic Ocean) side with the first nonzero. Once you start counting keep on counting. –2040

Atlantic-Pacific Rule u Pacific –If the decimal is present, start counting from the left (Pacific Ocean) side with the first nonzero. Once you start counting keep on counting. –

How many significant digits are in these numbers? u 2,339,009 u u u

Math with Significant Digits u When you add and subtract simply line up the decimals and keep the fewest places after the decimal in your answer. u = ? u – 30.0 = ?

Math with Significant Digits u When you multiply and divide, your answer should have the fewest digits shown in the original numbers. u 2.2 x 3 = ? u / 7.0 = ?

Density u A ratio of a substance’s mass to it’s volume u A constant value for a given substance no matter how much mass or volume u D = m/v u Units are a combination of mass and volume, ex. g/mL or kg/L

u A rock with a mass of 25.0 g has a volume of 5.0 mL, as determined by water displacement. What is the density of the rock?

u A wooden block with measurements of 2 cm, 3.0 cm, and 0.5 cm has a mass of 9.00 mg, what is the density of the wooden block?

Density Gradient Practical