1. Chapter 1, Introduction

2. Physics Honors Homework Due _____________________ Complete end of chapter problems: Begins on Pg. 27: 1, 2, 5, 7, 10, 11, 14, 15, 25, 26, 28, 37, 38, 45.

3. By the end of today… You will be able to tell other people what physics is all about. You will be able to explain the scientific method. You will be able to identify the SI units for the most common measurements. Day 1

4. Physics: The most basic of all sciences! Physics: The “Mother” of all sciences! Physics = The study of the natural world. Examines matter and energy and how they interact.

5. Things You Will Learn About in Physics http://commons.wikimedia.org/ wiki/Image:Flyingsuperconduct or.ogg velocity friction gravity Normal friction

6. Sub Areas of Physics This Semester : –Motion (MECHANICS) (most of our time!) –Gravitation, Energy Second Semester: –Electricity & magnetism –Light, sound, optics, and more

7. Physics: General Discussion Goal of Physics (& all of science): To quantitatively and qualitatively describe the “world around us”. Physics IS NOT merely a collection of facts and formulas! Physics IS a creative activity! Physics  Observation  Explanation. Requires: Calculation & IMAGINATION

8. How do Physicists come up with theories ? observeFirst, they observe a phenomenon in nature. scientific method:They often use the scientific method: 1.Recognize a problem 2.Make a hypothesis- an educated guess 3.Predict the consequences of the hypothesis 4.Perform experiments that test these predictions 5.Conclusion: Formulate the simplest, general rule that organizes and explains the hypothesis, prediction, and experimental outcome.

9. Scientific Method in Action! Car Crash Investigation: On the following slide, see if you can match the number or numbers on the right to the letter on the left

10. Match the number or numbers on the right to the letter on the left 1)Investigator might order blood alcohol test, check car parts, or try to reproduce marks on the road. 2)Investigator must reexamine evidence and possibly revise hypothesis. 3) Examine scene and fill out report. 4) Investigator goes to court, reexamines evidence, and defends his theory. 5) Maybe the driver fell asleep, was drunk, speeding, a tire exploded, breaks did not work, Scientific Method a)Observe and collect data b)Form and objectively test hypotheses by experiments c)Interpret Results and Revise Hypothesis if necessary. d)State Conclusions in a form others can evaluate

11. The Scientific Attitude Theories in science are not fixed. They may be supported by data and test results, but they are not facts. Example: The Model of the Atom The reviewing and changing of theories is a strength of science, and the heart of the scientific method. “No number of experiments can prove me right; a single experiment can prove me wrong.” ~ Albert Einstein

12. Chapter 1 Models Physics uses models that describe phenomena. A model is a pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept. A set of particles or interacting components considered to be a distinct physical entity for the purpose of study is called a system. Section 1 What Is Physics?

13. Chapter 1 Hypotheses Models help scientists develop hypotheses. A hypothesis is an explanation that is based on prior scientific research or observations and that can be tested. The process of simplifying and modeling a situation can help you determine the relevant variables and identify a hypothesis for testing. Section 1 What Is Physics?

14. Chapter 1 Hypotheses, continued Galileo modeled the behavior of falling objects in order to develop a hypothesis about how objects fall. If heavier objects fell faster than slower one’s, would two bricks of different masses tied together fall slower (b) or faster (c) than the heavy brick alone (a)? Because of this contradiction, Galileo hypothesized instead that all objects fall at the same rate, as in (d). Section 1 What Is Physics?

15. Looking Ahead… The rest of this week we will focus on reviewing measuring techniques for acquiring data. We will also review some basic math (YIKES!) that will be important for you to master. Linear Motion will then be the first step in understanding “Mechanics” – the broad Physics topic that we will focus on for the first half of this course.

16. Graphing 101: A Complete Review Bell-ringer 9/1/09 1.What is an independent variable? Where could you find it on a graph (which axis)? A variable that you change or manipulate. Usually it is graphed on the x-axis. 2.What is a dependent variable? Where could you find it on a graph (which axis)? A Variable that is not manipulated, but is observed (and often changes) as the independent variable is changed. Usually graphed on the y – axis. Day 2

17. What's Next? LAB We will focus on recording accurate Data and making logical Conclusions.

18. Spring/Rubber Band Activity Focus: 1.Identifying Variables 2.Collecting GOOD Data 3.Accurately Reporting Data (tables and graphs) 4.Analyzing the Results

19. A BAD GRAPH! Complete your graph from the Pulse Race Lab. Determine the Reaction Time per Person on the back of your graph paper.

20. Give the graph a title. Place labels on the x and y axis. Show units on the x and y axis. Do not play "connect the dots". Use a “best fit line” - a straight line which goes through the points or a curve that tends to follow them. Steps to Improve the Graph

21. A Better Graph ! Y-Axis X-Axis “Line of Best Fit” Dependent Variable Independent Variable

22. Relationships Between Variables The simplest relationship between two variables is a straight line or “linear” relationship. y=mx+b “slope-intercept” equation shows this relationship! m= slope m= slope (change in y divided by change in x)

23. Quick Review of Slope The slope of a line is defined as the rise over the run, m = Δy / Δx. Or m = (y 1 – y 2 ) / (x 1 – X 2 ) Change in Y Change in X Δ means change

24. Other Relationships Between Variables Inverse homepage.mac.com/cbakken/proportions/summary.html Quadratic (Square) y = ax 2 + bx + c

25. Concluding Chapter 1 By the end of today, you must be able to : Identify SI base units and Prefixes Convert measurements into scientific notation Distinguish accuracy from precision Day 3

26. Units: The SI System All measured physical quantities have units. Units are VITAL in physics!! In this course (and in most of the modern world, except the USA!) we will use (almost) exclusively the SI system of units. SI = “Systéme International” (French)

27. SI or “Metric” System 5 Most Commonly used SI units Length unit: Meter (m) Time unit: Second (s) Mass unit: Kilogram (kg) Temperature unit: Celsius (C) Electric Current unit: Amperes (A)

28. Prefixes Sometimes we need to measure things that are either very big or very small. In addition to the SI units, prefixes and scientific notation can be used to describe size.

29. Larger & smaller units defined from SI standards by powers of 10 & Greek prefixes How to use these prefixes

30. Powers of 10 (Scientific Notation) It is common to express very large or very small numbers using powers of 10 notation. Examples: 3,960 = 3.96  10 3 = 3.96x10x10x10 (moved decimal 3 places to left) 0.0021 = 2.1  10 -3 = 2.1/10/10/10 (moved decimal 3 places to right)

31. Example Problem 1 A housefly is about 5 millimeters wide. How many meters is this?

32. Example Problem 2 A football field is 48.8 meters wide. How many cm is this?

33. Example Problem 3 The mass of a mosquito is found to be 0.01 grams. Express this mass in kilograms using scientific notation.

34. Accurate vs. Precise Accurate – how close a measurement is to the “true” or “accepted” value. Precise – how repeatable or “consistent” measurements are.

35. Accuracy vs. Precision

36. Another Example 5 people measure a track stars time to be 49 seconds. If the correct or “true” value for the time was 60 seconds, we might say the measurements were “precise” (in other words consistent), but not accurate. If 5 people measured on or between 59 and 61 seconds, we would say their measurements were pretty accurate.

37. Precision (continued) Precision – the precision of a measuring device is limited by the intervals on that device.

38. Precision Example: see figure 11 page 17 -- a scale or measuring stick with only centimeters and half centimeters marked, could be “precise” down to a millimeter. Really we would be estimating the millimeter part of the reading.

39. Section III Unit One – Physics 9-3-09 Quiz to be completed by the end of the Hour Homework: finish reading chapter and review problems due Friday Day 3

40. Section III Objectives Students will be able to: Use dimensional analysis to proof equations Use order of magnitude estimations to check whether answers are reasonable.

41. Dimensional Analysis Example Density = mass / volume How could we use dimensional analysis to show that the equation: Volume = Density / mass is invalid?

42. Silent Reading & Quiz Students: Take 15-20 minutes to read pages 21-24 and answer problems 2, 4, & 5 on page 25.