1. Velocity, and Uniform Motion
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Velocity, and Uniform Motion

2. Speed, Velocity and Uniform Motion
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Speed = distance travelled per unit time
Represented by the symbol v (scalar quantity)
Average speed = total distance or Vavg = ∆d
time interval ∆t
Velocity = displacement of an object per unit time
Represented by the symbol (vector quantity)
Average velocity = displacement or
time interval

3. Constant speed = speed is the same during a period of time
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Constant speed = speed is the same during a period of time
Constant velocity = constant speed and also does not change direction
Constant velocity is sometimes referred to as uniform motion
Instantaneous speed = speed at a particular interval of time (radar!)

4. Example 1: Joe went 20 m[N] and then 20 m[S] in 2 minutes.
Calculate the speed
Calculate the velocity

5. Example 2:
A driver can travel at an average speed of 80 km/h on a level highway between two towns. It takes the driver 2 h to travel between the two towns. How far apart are the two towns?

6. Practice
Handout “Speedy Questions”

7. Investigation: Uniform Motion
Problem: How quickly can you move your hand and still have uniform motion?
Materials: - ticker timer - 1 m ticker timer tape
- metre stick
Procedure:
Set up the timer and thread one end of tap into it
While your partner operates the timer, hold on to the end of the tape and pull the tape as smoothly and as steadily as possible.
Select the first dot that is by itself and draw a line across the tape through it. Then, draw a line every sixth dot all the way through the tape. The six dots represent 0.10 s since the timer produces 60 dots per second.
metre stick
timer tape
ticker tape timer

8. Use the metre stick to determine the distance of each interval from the start position and record in an observation table
Plot the data on the graph with Time on the horizontal axis (x-axis) and Position on the vertical axis (y-axis).
Observations
t (s)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
(cm)

9. Questions:
Was your velocity uniform? How can you tell?
Find the average velocity for your motion in m/s and km/h
How would the graph change if you moved your hand more quickly? More slowly?