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Chapter 1-3 Outline

Chapter 1-3 Outline. Chapter 1. Introduction, Measurement, Estimating. Two branches of Physics:. 1-1 Nature of Science. Observations Includes designing and carrying out experiments Often have to use your imagination, as not every detail is always observed Theories

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Chapter 1-3 Outline

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  1. Chapter 1-3 Outline

  2. Chapter 1 Introduction, Measurement, Estimating

  3. Two branches of Physics:

  4. 1-1 Nature of Science • Observations • Includes designing and carrying out experiments • Often have to use your imagination, as not every detail is always observed • Theories • These are the other half of scientific process • Often derive from observations • Are formed and corrected through observations and experiments • Testing • Theories can be tested and supported, but they are never “proven” • This is due to an inexactness of measurement and lack of ability to test every possible theory, thus theories often change over time • Theories which are more general and explain more are accepted • The simpler theory is accepted

  5. 1-2 Physics and its Relation to Other fields • Physics has evolved from philosophy; physics is involved in most sciences

  6. 1-3 Models, Theories, and Laws • Model • analogy or imagery to explain phenomena • Theory • broader than a model (also testable) • Principle/Law • Laws are principles that have been found to be true in many cases

  7. 1-4 Measurement and Uncertainty: Significant Figures • Precision = consistency; Accuracy = correctness • Significant figures = non-zero numbers • Scientific Notation = M x 10n

  8. 1-5 Units, Standards, and the SI System • Measurements need units • Units need a standard, which defines what the unit is • Length = m, Time = s, Mass = kg • There are 7 base units: m, s, kg, A, K, mol, cd (we don’t use candela)

  9. 1-6 Converting Units • Use factor-label

  10. 1-7 Order of Magnitude: Rapid Estimating • This is how I want you to estimate answers to see if they are reasonable (using Sci Not)

  11. 1-8 Dimensional Analysis • Very important! Can help you determine what the equation should be

  12. Chapter 2 Describing Motion: Kinematics in One Dimension

  13. Chapter 2: 1-D Kinematics • Mechanics = the study of the motion of objects (force and energy) • Kinematics-HOW objects move • Dynamics-WHY objects move • Translational Motion = motion without rotation • Particle Model = we are only concerned how the object would move if it were a particle (i.e., it cannot rotate)

  14. 2-1 Reference Frames and Displacement • Reference frame = what the motion is relative to • Coordinate axis = same as in math class • Position = displacement from origin • Displacement = distance that has a direction and is relative to its starting point

  15. 2-2 through 2-4: Speed, Velocity, and Acceleration • Speed is the rate at which you travel • Average speed is the change in distance over the change in time • Velocity is speed with a direction • Average velocity is displacement over time • Instantaneous velocity is the velocity as the time interval approaches zero (infinitesimally small) • Acceleration is the rate at which the velocity changes

  16. 2-5 Constant Acceleration • Leads to the Kinematics equations • We use x for distance/position/displacement (technically position)

  17. 2-6 Solving Problems • Demonstrate #14, 15, 20, 30, 31 (Final three students will try on their own)

  18. 2-7 Falling Objects • All fall at the same rate, 10 m/s2

  19. 2-8 Graphical Analysis of Linear Motion • Same rules that we learned last year (slope of x-t is v, curvature is a; slope of v-t is a, area is displacement) • This year we will include acceleration-time graphs (a-t graph is the slope of the v-t graph, area under an a-t graph is the change in velocity) • Also, all graphs must be rounded off when changing between regions-you may not have a region that has an infinite slope or dotted lines

  20. Practice Problems • Problems: Pages 39-44 • Demonstrate: #14, 15, 20, 30, and 31 • Homework: Problems 21, 25, 39 (window in helicopter), 56, 84, and 85

  21. Chapter 3 Kinematics in Two Dimensions; Vectors

  22. Chapter 3: Kinematics in 2-D; Vectors • Projectile Motion: Objects projected outward near the surface of the Earth • Vectors are needed to use as a tool

  23. 3-1 Vectors and Scalars • Vector = has magnitude and direction • Scalar = no direction associated with them • Magnitude is represented by length, direction tip • Vectors are bold in the text

  24. 3-2 Addition of Vectors-Graphical Methods • If vectors are collinear, you may add them algebraically (one direction positive, opposite negative) • If vectors are at angles to one another, must use another method • Resultant is the net result when adding (multiplying) vectors • Tail-to-tip method is a way to add vectors

  25. 3-3 Subtraction of Vectors and Multiplication of a Vector by a Scalar • Subtracting is like adding a negative • To make a vector “negative,” reverse the direction • When multiplying by a scalar, change the magnitude of the vector only

  26. 3-4 Adding Vectors by Components • Components = parts of a vector that, when added together, make the original vector • Resolving = making a vector into its components • We use the x, y, and z components • x = rcosq • y = rsinq

  27. 3-5 Projectile Motion • Projectile Motion = motion in 2-D • Motion in one direction is independent of motion in the other direction

  28. 3-6 Solving Problems Involving Projectile Motion • Make an info box • Modified kinematics equations

  29. 3-7 Projectile Motion is Parabolic • Parametric Equations: x = v0xt y = v0y – ½ gt2

  30. 3-8 Relative Velocity • Velocities may be changed from one reference frame to another if you know how fast the frames are moving relative to one another

  31. Practice Problems • Problems: Pages 65-68 • Demonstrate: #31 • Homework: Problems #17, 18, 35, 30, and 41

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