2. Calculating Speed  Speed (S) : distance traveled (d) divided by  the amount of time it takes to travel (t). S = d  t OR S= d t

3. Units for Speed  Always a distance unit  by a time unit. Examples: Cars: mi/h Jets: km/h Snails: cm/s Falling objects: m/s

4.  If I travel 100 kilometer in one hour then I have a speed of…  100 km/h  If I travel 1 meter in 1 second then I have a speed of….  1 m/s S = d/t Let’s practice….

5. Average speed  Average speed = total distance traveled  total time. Do your parents always drive at the same speed?  NO!! So,  Speed is usually NOT CONSTANT, so we use “average speed” Examples: Cars stop at stoplights and speed up on the highway Runners go slower uphill than downhill Now, write your answer for Question #1

6.  It took me 1 hour to go 40 km on the highway. Then it took me 2 more hours to go 20 km using the streets.  Total Distance: 40 km + 20 km = 60 km  Total Time: 1 h + 2 h = 3 hr  Avg. Speed: total d/total t = 60 km/3 h = 20 km/h Let’s practice….

7. Question  I ran 1000 m in 3 minutes. Then ran another 1000 m uphill in 7 minutes. What is my average speed? A) 100 m/min B) 2000 m/min C) 10 m/min D) 200 m/min E) 20 m/min Total Dist. = 1000 m + 1000 m = 2000 m Total Time = 3 min + 7 min = 10 min Ave speed = total dist/total time = 2000m/10 min = 200 m/min = D Here’s one for you to try…. (Question #2)

8. Velocity  Velocity – the SPEED and DIRECTION of an object. Examples:  An airplane moving North at 500 mph  A missile moving towards you at 200 m/s Answer Question #3

9. Graphing Speed: Distance vs. Time Graphs Phoenix Denver

10. Graphing Speed: Distance vs. Time Graphs Answer Question #4

11. Graphing Speed: Distance vs. Time Graphs 3 h 600 km

12. Graphing Speed: Distance vs. Time Graphs 3 hours 600 km

13. Different Slopes Answer Question #5 Run = 1 hr Rise = 0 km Rise = 2 km Rise = 1 km Slope = Rise/Run = 1 km/1 hr = 1 km/hr Slope = Rise/Run = 0 km/1 hr = 0 km/hr Slope = Rise/Run = 2 km/1 hr = 2 km/hr

14. Question  Below is a distance vs. time graph of my position during a race. What was my AVERAGE speed for the entire race? Average Speed = Total distance/Total time = 12 km/6 hr = 2 km/hr Run = 6 hr Rise = 12 km Let’s try one….

15. Question  Below is a distance vs. time graph for 3 runners. Who is the fastest? Leroy is the fastest. He completed the race in 3 hours What do you think?

16. Acceleration Acceleration – the rate at which speed/velocity changes

17. Acceleration can be a(n): Increasing speed –Example: Car speeds up at green light Decreasing speed –Example: Car slows down at stop light Change in Direction –Example: Car takes turn (can be at constant speed) screeeeech

18. Calculating Acceleration If an object is moving in a straight line Units of acceleration: m/s 2, mph 2

19. 0 s 1 s2 s3 s4 s 0 m/s 4 m/s 8 m/s 12 m/s16 m/s Let’s try one together….

20. Question #6 A skydiver accelerates from 20 m/s to 40 m/s in 2 seconds. What is the skydiver’s average acceleration? Now, you try this one…

21. Graphing Acceleration: Use Speed vs. Time Graph 1)Inclined line= Speed is increasing with time or an increase in acceleration. 2)Line is straight = acceleration is constant 3)Flat Line???? Constant Speed

22. Graphing Acceleration continued: Speed vs. Time Graph 1)In Speed vs. Time graphs: Acceleration = Rise/Run = 4 m/s ÷ 2 s = 2 m/s 2 Run = 2 s Rise = 4 m/s

23. Remember when Graphing Speed: use Distance vs. Time Graphs On Distance vs. Time graphs 1) Curved line= shows the object is accelerating. **Remember slope = speed, so a curved line also means your speed is increasing because your slope is increasing.

24. Question #7: Above is a graph showing the speed of a car over time. 1) How is the speed of the car changing (speeding up, Slowing down, or staying the same)? 2) What is this car’s acceleration? 1)The car is slowing down 2)Acceleration = 0 – 12 / 6 = -12m/s ÷6s = -2 m/s 2 Run = 3 s Rise = -6 m/s Graphing Acceleration continued: Speed vs. Time Graph

25. 1)Which line represents an object that is accelerating? The black and red lines represent objects that are accelerating. Black is going a greater distance each second, so it must be speeding up. Red is going less each second, so what do you think it is doing? Remember: in distance vs. time graphs: curved line = accelerating, straight line = constant speed Pop Quiz!! Time (s) Slowing down Hint: Check out the x and y axes labels.

26. Comparing the graphs side-by-side… Speed Distance- Time Graph Stopped (m) (s) Shows acceleration… Shows speed…