AP Physics 1

1. AP Physics 1 Agenda for Today • Course Introduction • General Announcements • Structure of the course • Scope of the course • Begin chapter 1 Course Homepage: http://physicsgbhs.weebly.com/

2. General Announcements • Assignments: • Text: Glencoe Science: Physics Principles and Problems • Reading Assignment: Chapters 1 • Homework will do as Indicated on the Website and on the Board each day. • Lectures: (the PowerPoint component) will be posted at the course website • Videos:Selected YouTube videos will be availaible on line to help with learning the topcis

3. Grading • Several components: • Lecture: Occasional reading quizzes • Homeworkand Classwork (15%) • Exams: 40 % Tests 30% Quizzes • Class time: • Review homework, at most one day per week • Cooperative learning exercises • Labs: (15%) • Mostly worksheets

4. Act Lecture • Three main components: • Discussion class material • Selected topics from text • Demonstrations of physical phenomenon • Physics is an experimental science • Interactive exercise with conceptual “Active Learning” problems • Critical thinking and problem solving (Almost no memorization required)

5. Course Objectives • To begin to understand basic principles (e.g. Newton's Laws) and their consequences (e.g. conservation of momentum, etc.) • To solve problems using both quantitative and qualitative applications of these physical principles • To develop an intuition of the physical world

6. Scope of Physics 518 • Classical Mechanics: • Mechanics: How and why things work. Motion (dynamics), balance (statics), energy, vibrations, some thermodynamics Classical: • Not too fast (v << c), c ≡ speed of light • Not too small (d >> atom), atoms  10-9 m • Most everyday situations can be described in these terms. • Path of baseball (or a ping pong ball) • Path of rubber ball bouncing against a wall • Vibrations of an elastic string (Vibration Demo) (These reflect Newton’s Laws and forces) • Properties of matter; a roll of the dice (Thermodynamics)

7. This Week • Position and Time (Chapter 1) • What is Physics • Scientific Method • Vectors • Scientific Notation • Systems of units • Dimensional Analysis • Significant digits

8. Physics can also be described as the science of motion. What is Physics…..

9. Lab Scientific Method A step by step process where a scientist investigates a question by observing and performing experiments. Step 1 -  State the problem or pose a question Step 2 - Gather information (has someone already investigated this?) Step 3 - Form a hypothesis                            --  a possible explanation or answer

10. Step 4 - Test the hypothesis with an experiment Experiments have 2 variables Independent variable - what you change                                 Responding variable (dependent) - what you measure If you want to test the affect of fertilizer, you would add fertilizer to a plant (independent variable) and measure how the plant grows (responding variable) A control is something you do nothing to, used to compare your results you will also have a plant that receives no fertilizer

11. Step 5 - Conclusion Organize data into charts or graphs that can be read by others Step 6 - Draw Conclusions                   Determine if hypothesis is supported or rejected If hypothesis is not supported - modify hypothesis If hypothesis is supported - repeat experiment

12. Quick Review • Experiment: an organized procedure for testing a hypothesis...typically has a control and independent and dependent variables. • Control: a standard for comparison • Independent variable: the factor (or variable) that is changed by the experimenter • Dependent variable: the factor (or variable) that responds to change in the independent variable?

14. Metric System • Created by French scientists in 1798 – International System of Units (SI) – Units of different size related by powers of 10 • In USA, controlled by NIST (National Institute of Standards and Technology www.nist.gov)

15. Metric System • Fundamental or Base Unit: – a standard; a specific quantity – only seven (7) needed to describe all of nature

16. Metric System • To convert between SI units, multiply or divide by the appropriate power of 10. • Prefixes are used to change SI units by powers of 10, as shown in the table below.

17. The Prefixes Most Commonly Used

18. Conversion Between Units • A conversion factor is a multiplier equal to 1. For example, because 1 kg = 1000 g, you can construct the following conversion factors:

19. Conversion Between Units • Choose a conversion factor that will make the units cancel, leaving the answer in the correct units. • For example, to convert 1.34 kg of iron ore to grams, do as shown below:

20. Conversion Between Units • How many megahertz is 750 kilohertz? • Convert 5021 centimeters to kilometers. • How many seconds in a year? • Convert the speed 5.30 m/s to km/h (conversion miles to km is (1 Mile = 1.609344 km)

21. Scientific Notation • Physicists like to measure the very big, the very small and everything in between. • Earth is about 149,000,000,000meters from the Sun. • Scientific notation expresses a quantity as a numbertimes a power of 10. 1.49×1011 meters = 14.9×1010 meters = .149×1012 meters …. which is correct? • Proper format: M x 10nwhere1 M < 10

22. Standard Scientific Notation: A. Moving the decimal point to left exponent is ___________ number is _____ 1 5 positive 616000 = 6.16 x 10 left Shift ______ to here by ___ places > implied ________ decimal pt. 5 B. Moving the decimal point to right exponent is ___________ number is _____ 1 -3 0.0070 = 7.0 x 10 negative right Shift ______ to here by ___ places < 3

23. Ex: Convert to standard scientific notation 4.3 x 104 2.90 x 10-2 2.012 x 103 5 x 10-1 8 x 101 8.0 x 101

24. Measurements • We measure things to know something about them; to describe, to understand • Measurements must be accurate and mean the same to all • include 3 pieces of information – magnitude (how much) – units – uncertainty

25. Measurements • measurements are not numbers – numbers are obtained by counting or by definition; measurements are obtained by comparing an object with a standard "unit" – numbers are exact; measurements are inexact –mathematics is based on numbers; science is based on measurement

26. Measurement • Significant digits (sig figs) • Include all the numbers that can be read directly from the instrument scale plus one doubtful or estimated number. • Reflect the precision of the measurement. • Significant digits are considered only when calculating with measurements. • There is NO uncertainty with counting or exact conversions.

27. Figures (numbers) are significant if they are: • ________________ numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9 • any zeros that are: a. between any _________________ numbers: 509; or b. to the ___________ of a non-zero number AND to the ___________ of the decimal point: 0.00790; or c. between a non-zero number and the __________ _________ : 10. non-zero significant right right decimal point Ex: 5 2 4 3 1 1 2 2

28. 6 1 2 4 3 5 Ex 1: Measure the length of a box: L 4.7 cm = 4.7 ± 0.1 cm L = last digit is _____________ estimated

29. 6 1 2 4 3 5 Ex 2: Use a “better” ruler: L 0.01 cm = 4.67 ± L = 4.67 cm last digit is ______________ estimated

30. B. Sig. figs. when multiplying or dividing: answer has the _________ number of sig. figs., in this case: ____ 3 ____ sig. figs. lower 3.73 x 5.7 = 21 2 ____ sig. figs. 2 C. Sig. figs. when adding or subtracting: 3 18.541 +106.6 125.1 • ___ decimal places • ___ decimal places 1 lower answer has the _________ number of ___________________ , in this case: ____ decimal places 1

31. Measurement • Precision: –Degree of exactness –Reflects the ability to measure something – Limited by the smallest division on the measurement scale (least count) – Precision of a measurement is generally given as ± 0.1 the smallest division of the instrument • Accuracy: – closeness to a standard

33. Other Math Stuff

34. Dy VI. Slope = m = ________ Dx Steps: 1. Draw a best fit line using a __________ • Use two points on the line to calculate m: Steps: 1. Draw a best fit line using a __________ • Use two points on the line to calculate m: (x2, y2) = ( , ) ruler 8 32 40 30 y2 – y1 m = Dy = Dx = ________ = x2 – x1 20 32 - 5 8 - 1 10 (x1, y1) = ( , ) 1 5 3.9 0 0 6 8 2 4

35. Math in Physics:

36. Ball Bounce Lab TPFT 3.2 Combined with: Graph Analysis TPFT 3.3 Techniques of Graphing TPFT 3.4