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  1. Review and Announcements • Tatiana Brusentsova is the Teaching Assistant/Grader. • My office hours will take place in Room 402 of the Physics Department. • Make sure you are using WebAssign by the end of the week! Homework #1 due Monday.

  2. Chapter 2: One-Dimensional Kinematics • Outline • 2-1 Position, Distance, and Displacement • 2-2 Average Speed and Velocity • 2-3 Instantaneous Velocity • 2-4 Acceleration • 2-5 Motion with Constant Acceleration • 2-6 Applications of the Equations of Motion • 2-7 Freely Falling Objects

  3. Major Concepts • Position, distance and displacement • Speed and velocity • Average • Instantaneous • Constant • Acceleration • Average • Instantaneous • Constant • Graphs of position versus time, velocity versus time, and acceleration versus time • Equations of motion with constant acceleration • Free fall Warning Areas: Speed vs. Velocity Distance vs. Displacement Constant Velocity vs. Constant Acceleration

  4. Distance and displacement • Displacement is the net change in position from beginning to end of a journey • Distance is the total amount of change in position, including re-tracing your steps on the journey. Physics uses common terms in technical ways.

  5. Figure 2-2One-Dimensional Coordinates Try some examples…

  6. Speed and Velocity • Speed is the distance traveled in a period of time. It is a “scalar” (number only). • Velocity is the displacement in a period of time. It is a “vector” (number and direction).

  7. Distance and displacement What is the displacement at 1s, 2s, 3s, 4s? What is the distance traveled at 1, 2, 3, 4s?

  8. What is the average speed? • Greater than 40 mph. • Less than 40 mph. • Equal to 40 mph. Cross-Tab Label 0 / 100

  9. What is the average speed? • Greater than 40 mph. • Less than 40 mph. • Equal to 40 mph. Problem solving: -draw a picture -label all quantities -identify “unknown” -write down relationships (formulas), working backwards from unkown to known -find a formula for the unknown -plug in the numbers Etc. Cross-Tab Label 0 / 100

  10. Example 2-2Sprint Training Compare the average speed, and average velocity.

  11. Figure 2-4Motion Along the X Axis Represented with an x-Versus-tGraph

  12. Figure 2-5aAverage Velocity on an x-Versus-t Graph

  13. Figure 2-6Constant Velocity on an x-Versus-t Graph

  14. Figure 2-7Instantaneous Velocity

  15. Figure 2-8Graphical Interpretation of Average and Instantaneous Velocity

  16. Our first formula! If the velocity is constant, then the average velocity is the same as the instantaneous velocity. Rearranging:

  17. Acceleration • Acceleration is the change in velocity per unit time • The average acceleration is the change in velocity per change in time. It is a vector quantity.

  18. Figure 2-9v-Versus-t Plots for Motion with Constant Acceleration

  19. Our second formula! For constant acceleration… Velocity versus time produces a straight line graph, if acceleration is constant.

  20. Figure 2-10Graphical Interpretation of Average and Instantaneous Acceleration

  21. Example 2-3An Accelerating Train

  22. Cars Accelerating or Deceleratingwhich picture matches which graph? 1 2 3 4

  23. Figure 2-13aThe Average Velocity Special case: Constant acceleration Definition: change in velocity divided by time.

  24. Example 2-6Put the Pedal to the Metal

  25. Figure 2-16Velocity as a Function of Position for the Ranger in Example 2-8 Notice that ½ the speed is lost in last ¼ of stopping distance. CONSTANT DECELERATION

  26. Example 2-9aCatching a Speeder Q: How many mph?

  27. Table 2-4Constant-Acceleration Equations of Motion

  28. Figure 2-22Problem 2-3

  29. Figure 2-25Problem 2-17

  30. Figure 2-26Problem 2-21 Find the average velocity for each segment of the “walk”, and for the total “walk”. Now, compare DISPLACEMENT and DISTANCE. Compare, average VELOCITY and SPEED.

  31. Figure 2-28Problem 2-32 What is the average acceleration for each segment, what is the average acceleration for the whole motorcycle ride?

  32. Figure 2-29Problem 2-33 CAREFUL! What is the displacement for each segment of the graph shown? • Problem solving: • Draw a picture (given) • What are they asking for? • What is given? • What are the mathematical relationships?