Warm up: What is the scientific method? What is it used for?

The Scientific Method

The Scientific Method general approach to solving problems

The Scientific Method Step 1: State the problem. -Typically stated as a question

Step 2: Research the Problem The Scientific Method Step 2: Research the Problem Gather info, read journals, communicate with others

The Scientific Method Step 3: Hypothesizing proposing an explanation, theorizing, predicting, testable statement (if –then)

Step 4: Testing your hypothesis The Scientific Method Step 4: Testing your hypothesis experimenting

The Scientific Method Independent Variable The variable you change on purpose in the experiment

The Scientific Method Dependent Variable The response to the independent variable

The Scientific Method Control The group or experimental subject that does not receive the independent variable

The Scientific Method Constants Conditions that remain the same in the experiment

Step 5: Recording and analyzing the data The Scientific Method Step 5: Recording and analyzing the data Data tables and graphs of results

Step 6: Stating the conclusion The Scientific Method Step 6: Stating the conclusion What does the data/results mean, is the hypothesis correct?

The Scientific Method Step 7: Retesting Results are validated when experiments are repeated with the same results

The Scientific Method hypothesis is a testable statement that serves as a basis for making predictions and for carrying out further experiments

The Scientific Method model is usually proposed after a hypothesis is shown to be correct. A model that successfully explains many phenomena may eventually become part of a theory

The Scientific Method theory is a broad generalization that explains a body of facts or phenomena, and it is an extensively tested explanation for experimental results and explains why

The Scientific Method scientific law is a concise statement that summarizes the results of a broad variety of observations and experiments but does not try to explain it.

The Metric System and Measurement

Qualitative vs. Quantitative The following observations are qualitative. The building is really tall. It takes a long time for me to ride my bike to the store. I live really far away. The following observations are quantitative. The river is 31.5 m deep. The cheese costs $4.25 per pound. It is 75o F outside today. Critical Thinking Questions What is the difference between qualitative and quantitative observations?

SI System and Base Units The basic unit of length is the _____ and is measured by a _____

SI System and Base Units The basic unit of mass is a _____ and can be measured by a ______

SI System and Base Units The basic unit of time is _____ and it can be measured by a _____

SI System and Base Units The basic unit of Temperature is _____ and can be measured by a _____

SI System and Base Units

SI System and Base Units The basic unit for the amount of a substance is a mole

SI System and Base Units The basic unit for volume is the _____ and it can be measured with a ____ or a _____

SI System and Base Units

SI System and Base Units Density = _____/_____ The basic unit for density is _____, _____, or _____

SI System and Base Units

SI System and Base Units The basic unit for energy is a _____

Base Units and Prefix Handout SI System Base Units and Prefix Handout

Accuracy, Precision, and %Error

Warm up: Precision and Accuracy. Define precision. Define accuracy. Describe each situation. Is it accurate? precise? Both?

Accuracy measure of how close a measurement comes to the actual or true value of whatever is measured

Precision measure of how close a series of measurements come to one another

Precision and Accuracy

Accuracy and Precision

Accuracy and Precision

Accuracy and Precision Basketball free throws 99/100 shots are made 99/100 shots hit the rim 33/100 shots are made

Accepted vs. Experimental accepted value = the correct value based on reliable references experimental value = what was measured in the lab

Percent Error (Accepted – experimental) /accepted value x 100

Accuracy and Precision Density Experiment A: 2.00, 1.99, 2.01g/mL B: 2.50, 2.70, 2.90 g/mL Accepted value: 2.70g/mL

Uncertainty and Significant Figures

Significant Figures in measurement include all the digits that are known plus a last digit that is estimated. This last digit that is estimated is uncertain

Uncertainty of a Measuring Device take the smallest space and cut it in half

Uncertainty of a Measuring Device

Uncertainty of a Measuring Device

Figure 01-25-10UNEOC Title: Visualizing Concepts 1.6 (a) Caption: What is the length of the pencil in the figure if the scale reads in centimeters? How many significant figures are there in this measurement? [Section 1.5] Notes: Keywords:

Uncertainty of a Measuring Device

Counting Significant Figures Every nonzero digit in a reported measurement is assumed to be significant There are infinite sig figs when you are counting or dealing with exact quantities

Significant Figures There are infinite sig figs when you are counting or dealing with exact quantities

Rule for Determining Significant Zeros Rule 1: Zeros appearing between nonzero digits are significant

Rule for Determining Significant Zeros Rule 2: Zeros appearing in front of all nonzero digits are not significant

Rule for Determining Significant Zeros Rule 3: Zeros at the end of a number and to the right of the decimal point are significant

Rule for Determining Significant Zeros Rule 4: Zeros at the end of a number but to the left of the decimal point are not significant unless……

Rules for Rounding Numbers Rule 1: If the digit following the last digit to be retained is equal to or greater than 5 then the last digit should be increased by 1

Rules for Rounding Numbers Rule 2: If the digit following the last digit to be retained is less than 5 then the last digit should stay the same

Significant Figures In general, an answer cannot be more precise than the least precise measurement from which it was calculated.

Addition or Subtraction When adding or subtracting decimals, the answer must have the same number of digits to the right of the decimal point as there are in the measurement having the fewest digits to the right of the decimal point

Addition or Subtraction When working with whole numbers, the answer should be rounded so that the final digit is in the same place as the leftmost uncertain digit.

Multiplication and Division For multiplication or division, the answer can have no more significant figures than are in the measurement with the fewest number of significant figures .

The End