2. Introduction to Motion Position-Time Graphs Velocity-Time Graphs Acceleration-Time Graphs

3. First, Let’s define some important terms: Position Distance Displacement Speed Average velocity Instantaneous velocity Average Acceleration Instantaneous Acceleration

4. Position: Where it is. Distance: path length in meters; a scalar Displacement: final position minus initial position, in meters. Displacement is a VECTOR! r = 1 m distance = 2  m  x= 0 m

5. Speed: distance divided by total time, in m/s Average velocity: displacement divided by total time, in m/s. Velocity is a VECTOR! r = 1 m One revolution in 3.14 s. speed = 2 m/s v av = 0 m/s

6. A horse canters away from its trainer in a straight line, moving 150 m away in 14 s. It then turns abruptly and gallops halfway back in 4.5 s. Calculate a)its average speed for the entire trip and b)its average velocity for the entire trip. Use “away from the trainer” as the positive direction.

7. Instantaneous velocity: velocity at one point in time, in m/s. It is a VECTOR! t (s) x (m)

8. Average Acceleration: rate of change of velocity, in m/s 2. It is a VECTOR! Instantaneous Acceleration: acceleration at one point in time, in m/s 2. Also a VECTOR!

9. Graph things every physics student should know: Y-interceptSlopeArea under curve x vs. t v vs. t a vs. t Initial position, x 0 Initial velocity, v 0 Initial acceleration, a 0 velocity acceleration Jerk Nothing Displacement Change in Velocity

10. WALK THIS WAY: x t

11. x t

12. x t

13. x t

14. x t Y-intercept? Slope?

15. WALK THIS WAY (NOTE - VELOCITY GRAPH): v t

16. v t

17. v t Y-intercept? Slope? Area under curve?

18. WALK THIS WAY (NOTE – ACCELERATION GRAPH): a t

19. a t Y-intercept? Area under curve? Slope?

20. t (s) v (m/s) 25 15 5 0 20 10 5 20 15 Draw the corresponding acceleration-time graph: Draw the corresponding position-time graph.

21. Summarize! Review your notes for three minutes and mark the key ideas from the discussion. Then, trade with a partner to see if you have marked the same things.

22. Graph things every physics student should know: Y-interceptSlopeArea under curve x vs. t v vs. t a vs. t Initial position, x 0 Initial velocity, v 0 Initial acceleration, a 0 velocity acceleration Jerk Nothing Displacement Change in Velocity

23. Notation Delta,  Subscripts – i, 0 – f –0, I, 2

24. Common word problem phrases Starts from rest…v 0 =0...after __ sec…  t=___ Comes to rest, v f =0 Initial…at time =0 Moves a total of _ meters…  x=__ …max height…v @ h max =0, and  h=