1. Measuring Motion

2. Observing Motion Must observe object in relation to another object that appears to stay in place. (reference point) Change position over time when compared with a reference point. (motion) Need to describe direction.

3. Speed Speed = rate at which object moves. Speed depends on distance traveled and the time taken to travel that distance. The SI unit for speed is meters per second (m/s).

4. Determining Average Speed Average Speed = total distance total time

5. Math Break 1.If you walk for 1.5 hrs. and travel 7.5 km, what is your average speed? If the average speed of a car is 110 km/h, how long will it take the car to travel 715 km?

6. Velocity: Direction Matters Here’s a riddle for you: Two birds leave the same tree at the same time. They both fly at 10 km/h for 1 hour, 15 km/h for 30 minutes, and 5 km/h for 1 hour. Why don’t they end up at the same destination?

7. Velocity cont. Riddle answer: Different directions, which means that they have different velocities. The speed of an object in a particular direction is the object’s velocity. You MUST include direction when writing or talking about velocity. Example: airplane’s velocity Correct – 600 km/h south Incorrect – 600 km/h

8. Velocity Exercise Which of the following are examples of velocity? a.25 m/s forward b. 1,500 km/h c. 55 m/h south d. All of the above

9. Velocity Cont. Constant Velocity = no change in its speed or direction (always along a straight line) Examples: If you’re riding in a bus traveling east at 15 m/s, you and all the other passengers are also traveling at a velocity of 15 m/s east. But suppose you stand up and walk down the bus’s aisle while it is moving. Are you still moving at the same velocity as the bus?

10. Velocity Cont. NO! Below shows how you can combine velocities to determine the resultant velocity. 15 m/s east + 1 m/s east = 16 m/s east 15 m/s east – 1 m/s west = 14 m/s east

11. Assignment Write a paragraph (to hand in) that gives examples of when it is sufficient to know only the speed of something and when it is important to know the velocity. **** Must be at least 6 sentences long!