2. Speed

3. Warm up What 2 measurements do you need to know to find the speed of something? What is the difference between speed & velocity?

4. Warm up What 2 measurements do you need to know to find the speed of something? Distance & time

5. Warm up What is the difference between speed & velocity? Speed is distance / time Velocity is speed & direction

6. A dog travels 20 meters and it takes 2.5 seconds. What is the dog’s speed? Speed = distance time 20 = 8 m/s 2.5

7. “Speed Machines” Worksheet Check your answers Be sure to find the speed in miles/hour

8. 600 600 = 150 m/h 4 380 = 760 m/h.5

9. 800 = 320 m/h 2.5 239 = 318.67 m/h.75

10. A. 2200 x 2 = 4400 miles B. 2200 x 3 = 6600 miles C. 2200 x 5 = 11,000 miles

11. Speed Activity Mrs. Pafundi ran 1 mile in 10.37 min. 1 mile__ 11 min.09 mile X 60 min 1 min 1 hr =.09 mi/min = 5.4 mi/hr Step 1 Step 2 How many miles/hr? Step 3 5.4 mi X 1.609 km 1 hr 1 mi = 8.7 km/hr

12. Acceleration

13. Acceleration Acceleration – rate at which velocity (speed & direction) changes Occurs when any of these happen: Increase speed example: Decrease speed (also called deceleration) example: Change direction example:

14. Acceleration acceleration = final velocity – initial velocitytime example: An airplane starts and travels 40 m/s after 5 seconds. What is its acceleration? 40 m/s - 0 m/s = 40m/s = 8m/s/s = 8 m/s 2 5s 5s

15. Warm-up Set up the equation and then solve. Use your notes. 1. As a roller coaster starts down a slope, its velocity is 4m/s. But 3 seconds later, its velocity is 22m/s in the same direction. What is its acceleration? Initial velocity = Final velocity = Time = 4 m/s 22 m/s 3 s 22 m/s - 4 m/s 3 s = 18 m/s 3 s = 6 m/s 2

16. Warm-up Set up the equation and then solve. Use your notes. 1. A falling raindrop accelerates from 10 m/s to 30 m/s in 2 seconds. What is its acceleration? Initial velocity = Final velocity = Time = 10 m/s 30 m/s 2 s 30 m/s - 10 m/s 2 s = 20 m/s 2 s = 10 m/s 2

17. Warm-up Set up the equation and then solve. Use your notes. 1. A certain car can accelerate from rest to 27 m/s in 9 seconds. What is its acceleration? Initial velocity = Final velocity = Time = 0 m/s 27 m/s 9 s 27 m/s - 0 m/s 9 s = 27 m/s 9 s = 3 m/s 2