1. 1 Constant & Changing Motion

2. 2 Reference Point A fixed point from which direction is defined. The reference point can be anything.

3. 3 Distance The length traveled measured from start to finish. Use meters!!!

4. 4 Example #1 A car drives 4 meters north, 3 meters south, then 5 meters north. What’s its total distance driven? D = 4m + 3m + 5m D = 12m

5. 5 Direction Represented by using : (+) or (-) signs Up or Down Right or Left Forward or Backward North, South, East or West

6. Magnitude The amount of something. 6

7. Scalar Has an amount described by a single number –Example: Time –Has magnitude only –Only positive 7

8. 8 Position Where something is, relative to the reference point.

9. Vector Has magnitude and direction –Example: acceleration –Can be positive or negative 9

10. 10 Displacement The net difference between the starting point and the ending point.  d = d final – d initial

11. 11 Example #2 A car drives 4 meters north, 3 meters south then 5 meters north. What’s its displacement? Δd = 9m north – 3m south Δd = 6m north These are the vectors that we’ve been practicing!

12. 12 Time Interval The difference between two clock readings  t = t final – t initial Use seconds!!!

13. 13 Speed Total distance traveled divided by the total time elapsed. speed = distance/time

14. 14 Average Velocity ( V avg ) Total distance traveled divided by the total time elapsed. V avg =  d/  tUnits: m/s Magnitude (size) and direction

15. 15 Average Velocity 1 mile2 miles 3 seconds1 second2 minutes home Dairy Queen 4 hr. EXXON 3 hr. 5 miles Δt includes ALL time, whether you were moving or not! Δt = 1 sec + 14400 sec + 120 sec + 10800 sec + 3 sec Δt = 25324 sec (x 1 hr / 3600 sec = 7.03 hr) V avg = 5 mi / 7.03 hr V avg = 0.71 mi/hr LHS

16. 16 What is the difference between speed and velocity? Velocity is a vector quantity (magnitude & direction) Speed represents the magnitude of velocity (scalar quantity)

17. 17 Instantaneous Velocity (V) Velocity at one point Δd and Δt are very, very, very, very……small!

18. 18 Constant Velocity If a body is moving at a constant velocity, the velocity never changes between intervals. Doesn’t happen often in real life! Ex: V = 10 m/s

19. 19 Changing Velocity Here, the velocity changes between intervals. Ex: V = 10 m/sV = 15 m/sV = 20 m/s

20. 20 Acceleration Acceleration is the change in velocity over time. Average acceleration (a avg ) = change in velocity time spent a avg = ΔV / Δt Units: (m/s)m ss 2

21. 21 Acceleration Example #1 Find a avg. V i = 10 m/sV f = 40 m/s a avg = 40 – 10 m/s 2 s *This means that the object’s velocity increases 15m/s every second! a avg = 15 m/s 2 Δt = 2 sec

22. 22 Acceleration Example #2 Find a avg. V i = 40 m/sV f = 10 m/s a avg = 10 – 40 m/s 2 s *This means that the object’s velocity decreases 15m/s every second! a avg = - 15 m/s 2 Δt = 2 sec

23. 23 Acceleration Example #3 Find a avg. V i = 40 m/sV f = 40 m/s a avg = 40 – 40 m/s 2 s *This means that the object’s velocity is constant! a avg = 0 m/s 2 Δt = 2 sec

24. 24 Four Basic Equations of Physics Conditions: –One-dimensional motion –Constant acceleration

25. 25 Four Basic Equations of Physics V f = V i + at d = V i t + ½ at 2 2ad = V f 2 – V i 2 V f + V i 2 d =t