1. Speed and Velocity Physics Part 8

2. Speed The distance an object moves in a certain amount of time. A scalar quantity. v Most common units are m/s and km/h.

3. Speed Slope of a distance-time graph.

4. Speed

5. Constant and Changing Speeds Constant speed occurs when an object travels the same distance for each time interval. Uniform motion. Changing speed occurs when an object travels a different distance for each time interval.

6. Average Speed Uses the total distance travelled.

7. Instantaneous Speed The speed at a specific instant of time.

9. Example 1 A bird is observed to fly 50 meters in 7.5 seconds. Calculate the speed of the bird.

10. Example 2 The CN Tower elevator in Toronto can attain a speed of 7.11m/s. How much time would the elevator take to climb 37.5m (about 10 stories)?

11. Velocity The change in an object’s position over time. The speed of an object and the direction it is travelling. A vector quantity. → v

12. Velocity Slope of a position-time graph.

13. Velocity

14. Because it is a vector, velocity can be positive, negative, or zero.

15. Example 1 A hiker has travelled 5km North in 2 hours. Calculate her average velocity.

16. Example 2 A super awesome science teacher (ahem) walked 4m east, 2m south, 4m west, and 2m north. The entire motion lasted 24 seconds. Determine the super awesome science teacher’s average velocity.

17. Practice 1. How long does it take a rabbit to hop 500m if he can travel at an average speed of 4m/s? 2. How far does a car travel if it moves at a velocity of –50km/h for 4.5 hours? 3. How fast does a cyclist need to go in order to complete 12km in 30min?

18. Speed vs Velocity Usain Bolt’s Speed Bolt vs Cheetah