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# Ch 1: Introduction and Math Concepts

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### Ch 1: Introduction and Math Concepts

1. 1. Chapter 1 Introduction and Mathematical Concepts
2. 2. Table of Contents <ul><li>The Nature of Physics </li></ul><ul><li>Units </li></ul><ul><li>Role of Units in Problem Solving </li></ul><ul><li>Trigonometry </li></ul><ul><li>Scalars and Vectors </li></ul><ul><li>Vector Addition and Subtraction </li></ul><ul><li>Components of a Vector </li></ul><ul><li>Addition of Vectors by Means of Components </li></ul><ul><li>Other Stuff </li></ul>
3. 3. Chapter 1: Introduction and Mathematical Concepts Section 1 – The Nature of Physics
4. 4. What is Physics? <ul><li>The “Fundamental Science” </li></ul><ul><li>Study of matter and how it moves through space-time </li></ul><ul><ul><li>Applications of concepts such as Energy, and Force </li></ul></ul><ul><li>The general analysis of the natural world </li></ul><ul><ul><li>“understand” and predict how our universe behaves </li></ul></ul>
5. 5. Chapter 1: Introduction and Mathematical Concepts Section 2 - Units
6. 6. Units <ul><li>To “understand” nature, we must first study what it does </li></ul><ul><li>Must have/use a universal way of describing what nature does </li></ul><ul><li>Systems of measurement </li></ul><ul><ul><li>“British” (American) </li></ul></ul><ul><ul><li>Metric </li></ul></ul><ul><ul><li>SI </li></ul></ul>
7. 7. Base Units <ul><li>Most fundament forms of measurement </li></ul><ul><ul><li>Mass – kilogram (kg) </li></ul></ul><ul><ul><li>Length – meter (m) </li></ul></ul><ul><ul><li>Time – second (s) </li></ul></ul><ul><ul><li>Count – mole (mol) </li></ul></ul><ul><ul><li>Temperature – kelvin (K) </li></ul></ul><ul><ul><li>Current – ampere (A) </li></ul></ul><ul><ul><li>Luminous Intensity – candela (cd) </li></ul></ul>
8. 8. SI Features <ul><li>Derived Units </li></ul><ul><ul><li>Common combinations of base units </li></ul></ul><ul><ul><li>e.g.: area, force, pressure </li></ul></ul><ul><li>Prefixes </li></ul><ul><ul><li>Adjust scale of measurement </li></ul></ul><ul><ul><li>Metric – powers of 10 </li></ul></ul><ul><ul><li>SI – powers of 1000 </li></ul></ul>
9. 9. SI Prefixes <ul><li>10 24 yotta (Y) </li></ul><ul><li>10 21 zetta (Z) </li></ul><ul><li>10 18 exa (E) </li></ul><ul><li>10 15 peta (P) </li></ul><ul><li>10 12 tera (T) </li></ul><ul><li>10 9 giga (G) </li></ul><ul><li>10 6 mega (M) </li></ul><ul><li>10 3 kilo (k) </li></ul><ul><li>10 -3 milli (m) </li></ul><ul><li>10 -6 micro (µ) </li></ul><ul><li>10 -9 nano (n) </li></ul><ul><li>10 -12 pico (p) </li></ul><ul><li>10 -15 femto (f) </li></ul><ul><li>10 -18 atto (a) </li></ul><ul><li>10 -21 zepto (z) </li></ul><ul><li>10 -24 yocto (y) </li></ul>
10. 10. Chapter 1: Introduction and Mathematical Concepts Section 3 The Role of Units in Problem Solving
11. 11. Conversion of Units <ul><li>Remember from algebra… </li></ul><ul><ul><li>Multiplying by 1 does not change number </li></ul></ul><ul><li>If 1 m = 1000 mm, then </li></ul><ul><ul><li>1 m/1000 mm = 1 </li></ul></ul>
12. 12. Question #1 <ul><li>When we measure physical quantities, the units may be anything that is reasonable as long as they are well defined. It’s usually best to use the international standard units. Density may be defined as the mass of an object divided by its volume. Which of the following units would probably not be acceptable units of density? </li></ul><ul><li>a)gallons/liter b)kilograms/m 3 c)pounds/ft 3 </li></ul><ul><li>d)slugs/yd 3 e)grams/milliliter </li></ul>
13. 13. Question #2 <ul><li>A car starts from rest on a circular track with a radius of 150 m. Relative to the starting position, what angle has the car swept out when it has traveled 150 m along the circular track? </li></ul><ul><li>a) 1 radian b)  /2 radians c)  radians </li></ul><ul><li>d) 3  /2 radians e) 2  radians </li></ul>
14. 14. Question #3 <ul><li>A section of a river can be approximated as a rectangle that is 48 m wide and 172 m long. Express the area of this river in square kilometers. </li></ul><ul><li>a) 8.26 × 10  3 km 2 b) 8.26 km 2 </li></ul><ul><li>c) 8.26 × 103 km 2 d) 3.58 km 2 </li></ul><ul><li>e) 3.58 × 10  2 km 2 </li></ul>
15. 15. Question #4 <ul><li>If one inch is equal to 2.54 cm, express 9.68 inches in meters. </li></ul><ul><li>a) 0.262 m b) 0.0381 m </li></ul><ul><li>c) 0.0508 m d) 0.114 m </li></ul><ul><li>e) 0.246 m </li></ul>
16. 16. Dimensional Analysis <ul><li>When in doubt, look at the units </li></ul><ul><li>Since units are part of the number, units must balance out for a valid equation </li></ul><ul><li>By analyzing the units, you can determine if your solution is correct. </li></ul><ul><li>If the units from your calculation do not give you the units you need, you have an error </li></ul>
17. 17. Example DIMENSIONAL ANALYSIS [L] = length [M] = mass [T] = time Is the following equation dimensionally correct?
18. 18. Question #5 <ul><li>Using the dimensions given for the variables in the table, determine which one of the following expressions is correct. </li></ul><ul><li>a) </li></ul><ul><li>b) </li></ul><ul><li>c) </li></ul><ul><li>d) e) </li></ul>
19. 19. Question #6 <ul><li>Given the following equation: y = c n at 2 , where n is an integer with no units, c is a number between zero and one with no units, the variable t has units of seconds and y is expressed in meters, determine which of the following statements is true. </li></ul><ul><li>a) a has units of m/s and n =1. </li></ul><ul><li>b) a has units of m/s and n =2. </li></ul><ul><li>c) a has units of m/s 2 and n =1. </li></ul><ul><li>d) a has units of m/s 2 and n =2. </li></ul><ul><li>e) a has units of m/s 2 , but value of n cannot be determined through dimensional analysis. </li></ul>
20. 20. Question #7 <ul><li>Approximately how many seconds are there in a century? </li></ul><ul><li>a) 86,400 s </li></ul><ul><li>b) 5.0 × 10 6 s </li></ul><ul><li>c) 3.3 × 10 18 s </li></ul><ul><li>d) 3.2 × 10 9 s </li></ul><ul><li>e) 8.6 × 10 4 s </li></ul>
21. 21. Chapter 1: Introduction and Mathematical Concepts Section 4 - Trigonometry
22. 22. Basics you should remember…
23. 23. Basics you should remember…
24. 24. Question #8 <ul><li>Determine the angle  in the right triangle shown. </li></ul><ul><li>a) 54.5  </li></ul><ul><li>b) 62.0  </li></ul><ul><li>c) 35.5  </li></ul><ul><li>d) 28.0  </li></ul><ul><li>e) 41.3  </li></ul>
25. 25. Question #9 <ul><li>Determine the length of the side of the right triangle labeled x . </li></ul><ul><li>a) 2.22 m </li></ul><ul><li>b) 1.73 m </li></ul><ul><li>c) 1.80 m </li></ul><ul><li>d) 2.14 m </li></ul><ul><li>e) 1.95 m </li></ul>
26. 26. Question #10 <ul><li>Determine the length of the side of the right triangle labeled x . </li></ul><ul><li>a) 0.79 km </li></ul><ul><li>b) 0.93 km </li></ul><ul><li>c) 1.51 km </li></ul><ul><li>d) 1.77 km </li></ul><ul><li>e) 2.83 km </li></ul>
27. 27. Chapter 1: Introduction and Mathematical Concepts Section 5 – Scalar & Vectors
28. 28. Scalar & Vector <ul><li>A scalar quantity is one that can be described by a single number: </li></ul><ul><ul><li>temperature, speed, mass </li></ul></ul><ul><li>A vector quantity deals inherently with both magnitude and direction: </li></ul><ul><ul><li>velocity, force, displacement </li></ul></ul>
29. 29. More on Vectors <ul><li>Arrows are used to represent vectors. The direction of the arrow gives the direction of the vector. </li></ul><ul><li>By convention, the length of a vector arrow is proportional to the magnitude of the vector. </li></ul>8 lb 4 lb
30. 30. Question #11 <ul><li>Which one of the following statements is true concerning scalar quantities? </li></ul><ul><li>a) Scalar quantities must be represented by base units. </li></ul><ul><li>b) Scalar quantities have both magnitude and direction. </li></ul><ul><li>c) Scalar quantities can be added to vector quantities using rules of trigonometry. </li></ul><ul><li>d) Scalar quantities can be added to other scalar quantities using rules of trigonometry. </li></ul><ul><li>e) Scalar quantities can be added to other scalar quantities using rules of ordinary addition. </li></ul>
31. 31. Chapter 1: Introduction and Mathematical Concepts Section 6 Vector Addition and Subtraction
32. 32. Graphical Addition of vectors <ul><li>Remember length of arrow is proportional to magnitude </li></ul><ul><li>Angle of arrow proportional to direction </li></ul><ul><li>Place tail of 2 nd vector at tip of 1 st </li></ul><ul><li>Resultant starts at 1 st and ends at 2 nd </li></ul>
33. 33. Graphical Subtraction of Vectors <ul><li>Same as addition, multiply value by (-1) </li></ul><ul><li>Resultant is still tail to tip </li></ul>
34. 34. Question #12 <ul><li>Which expression is false concerning the vectors shown in the sketch? </li></ul><ul><li>a) </li></ul><ul><li>b) </li></ul><ul><li>c) </li></ul><ul><li>d) C < A + B </li></ul><ul><li>e) A 2 + B 2 = C 2 </li></ul>
35. 35. Chapter 1: Introduction and Mathematical Concepts Section 7 Components of a Vector
36. 36. Vector Component
37. 37. Scalar Components It is often easier to work with the scalar components rather than the vector components. In math, they are called i and j
38. 38. Example Problem <ul><li>A displacement vector has a magnitude of 175 m and points at an angle of 50.0 degrees relative to the x axis. Find the x and y components of this vector. </li></ul>
39. 39. Question #13 <ul><li>During the execution of a play, a football player carries the ball for a distance of 33 m in the direction 76° north of east. To determine the number of meters gained on the play, find the northward component of the ball’s displacement. </li></ul><ul><li>a) 8.0 m b) 16 m </li></ul><ul><li>c) 24 m d) 28 m </li></ul><ul><li>e) 32 m </li></ul>
40. 40. Question #14 <ul><li>Vector has components a x = 15.0 and a y = 9.0. What is the approximate magnitude of vector ? </li></ul><ul><li>a) 12.0 b) 24.0 </li></ul><ul><li>c) 10.9 d) 6.87 </li></ul><ul><li>e) 17.5 </li></ul>
41. 41. Question #15 <ul><li>Vector has a horizontal component a x = 15.0 m and makes an angle  = 38.0  with respect to the positive x direction. What is the magnitude of a y , the vertical component of vector ? </li></ul><ul><li>a) 4.46 m b) 11.7 m </li></ul><ul><li>c) 5.02 m d) 7.97 m </li></ul><ul><li>e) 14.3 m </li></ul>
42. 42. Chapter 1: Introduction and Mathematical Concepts Section 8 Addition of Vectors by Means of Components