1. 2.1 to 2.3 Displacement, Velocity, and Acceleration

2. 2.1 Displacement Mechanics –Kinematics Describes motion –Dynamics Describes effects of forces on motion

3. Displacement Change in position x 0 = initial position x = current position  x = displacement

4. Displacement  x = x – x 0 Meter In 1-D –Right is positive –Left is negative

5. Displacement vs. Distance Displacement = final pos – initial pos Distance = total distance traveled

6. Speed vs. Velocity No Direction m/s Direction m/s

7. Average Velocity The football player ran 50 m in 20 s. What is his average velocity? v = 50 m / 20 s = 2.5 m/s

8. Your turn The little kid ran 35 m, then turned and ran 15 m back. If he started running at 1:05:00 and ended at 1:06:10, what was his average speed? Average velocity?

9. Instantaneous Velocity How fast going at this instant As t  small, –Average velocity  instantaneous velocity

10. 2.3 Acceleration Describes changes in velocity +  faster -  slower 0  constant velocity Units: m/s 2

11. Ave a vs. instant a

12. Acceleration A car goes from 0 to 100 m/s in 6 s. What is its average acceleration? a = 100 m/s / 6 s = 16.7 m/s 2 v = 100 m/s a = 16.7 m/s 2

13. Your turn A racecar traveling at 320 km/h hits a barrier and stops in 2 s. What was the average acceleration? (Don’t forget to convert to m/s!) a = -44.5 m/s 2 v = 88.9 m/s a = -44.5 m/s 2

14. Practice Work You can complete 48 #CQ1 – 5, P1 – 5, 7 – 9, 12 – 15 Total of 17 problems