1. Motion and Force
8SCIENCE

2. What is motion?
All objects start in a position or place and this changes as the object moves
We can sense how fast objects are moving
insects crawling on a window, people crossing the street
To describe how fast objects are moving, we talk about speed
Speed is the rate of change in a position, usually in km/h or m/s (meters/second)

3. Speed
Speed can be described at an exact moment in time or you can describe average speed
Example: If you travel 80m (meters) in 40s (seconds) what is your speed?
Average speed can be determined by dividing the total distance travelled by the time it takes
Average speed (s) = total distance (d)
total time (t)
Example: if someone ran 100 meters in 20 seconds, then ran another 100 meters in 25 seconds, what would be the average speed for the 200 meters?

4. Speed
At rest – not moving
Speed changes at a constant rate

5. Speed and direction The direction of the motion can also be important
Displacement is the change in position of an object and includes direction
Need the start and end points to calculate
Ex: What is this person’s displacement if they begin at A
and travel to point C?
- 5 meters

6. Velocity When speed is combined with a direction, we have velocity
Example speed: I was driving at 30km/h.
Example velocity: I drove 30km/h north of the school.
Velocity is the rate of change of displacement
Velocity (v) = displacement (d)
time (t)
Ex: If you run around a 6 km circular track in 60 minutes (1 hour) What is your average speed (in km/h)?
What is your velocity?