1. Introduction to One- Dimensional Motion

2. Quantities associated with motion Scalar Quantities do not have direction. Scalar quantities only have magnitude (how much) Ex: 15 meters, 28 km/s Vector Quantities have both magnitude and direction. Ex: 15 meters to the right, 28 km/s to the North

3. What’s the difference between distance and displacement? Distance: the total magnitude traveled For example, if you have to take the long way around a traffic jam, your distance increases Displacement: the shortest distance from the starting point to the ending point Draw & label this picture on your notes

4. What is average speed?

5. What is Average Velocity?

6. Units For Speed and Velocity In science, we use the metric system and distance & displacement are measured in meters (m) Time is measured in seconds (s) no matter what measurement system you are using Therefore, speed and velocity are both measured in the same units (m/s)

7. Speed & Velocity Examples Speed is distance divided by time 2 cm/s Velocity is displacement divided by time and includes and has direction 2 cm/s west West

8. More Velocity Examples If the runner goes around a 400m circular track 2 times, what is his displacement? Straight line distance from beginning to end = zero What is the distance covered? 2 times the circumference of the circle = 800m

9. Try these Speed/Velocity Problems #1 and #2 1. A car travels 1000 m in 50s. What is the car’s speed? Speed = distance/time = 1000 m/50 s = 20 m/s 2. A car travels 1000 m north in 50s. What is the car’s velocity? Velocity = displacement/time = 1000 m/50 s = 20 m/s, north

10. Sample Problem #3 A car travels 500 m east, 1000 m west and then 2000 m east again. It does this in a time of 100 seconds. What is the car’s average speed? Speed = distance/time = 3500 m/100 s = 35 m/s What is the car’s average velocity? Velocity = displacement/time = 1500 m east/100 seconds = 15 m/s, east

11. What is the difference between average velocity and instantaneous velocity? Average Velocity: Total Displacement divided by total time Instantaneous Velocity: Velocity at a certain moment in time Ex: A school bus takes 45 seconds to travel 25 meters. What is the average velocity? What is the instantaneous velocity when it stops?

12. Using Graphs to Calculate Speed

13. Practice Problems 1.A dog runs 15.3 m/s for 32 seconds. How far does he go? 2.How long does it take to go 12 m in a car travelling 28 m/s? 3.What is the speed of an airplane that flies 2000 km for 2.5 hours?

14. Practice Problems