1. S8P3. Students will investigate relationship between force, mass and the motion of objects.

2. Motion When an object changes position over time relative to a reference point (the object that appears to stay in place), the object is in motion. You can describe the direction of the motion with reference direction like north, south, east and west.

3. Speed Speed is the distance traveled by an object divided by the time taken to travel that distance The SI unit is m/s (meters/second), km/h (kilometers/hour), mi/h (miles per hour).

4. Calculating Speed Average speed = total distance total time If you traveled 360 km for 4 hours what was your average speed? Average speed = 360 km = 90 km/h 4 h

5. Velocity Velocity – is the speed of an object in a particular direction. Example – 600 km/h south Imagine that 2 birds leave the same tree at the same time. They both fly at 10 km/h for 4 min, 12 km/h for 8 min, and 5 km/h for 10 min. Why don’t they end up at the same place? Answer: They went in different directions!

6. Changing Velocity An objects velocity changes if either its speed or direction changes. Example: 15 m/s south speeds up to 20 m/s south Example: If the bus travels at the same speed but changes direction

7. Acceleration Acceleration – is the rate at which velocity changes over time; an object accelerates if it speed, direction, or both change. Positive acceleration – increase in velocity Negative acceleration – decrease in velocity

8. Acceleration Average acceleration = final velocity – starting velocity time it takes to change velocity Look at Figure 5 on page 122 Average acceleration = 5 m/s - 1 m/s = 1 m/s 2 south 4s

9. Class Work Answer questions 3 – 11 on page 123 This assignment will be turned in for a grade