This document discusses key concepts related to speed, velocity, distance, and time. It defines speed as distance over time, velocity as the rate of change of displacement, and distinguishes between average and instantaneous speed. The document provides an example of calculating Usain Bolt's speed using the distance and time it took him to run 100 meters. It notes that while distance traveled may be large, displacement can be zero if the starting and ending points are the same. Finally, it instructs the reader to draw and interpret distance-time and velocity-time graphs related to everyday journeys.

1. February 16, 2011
Speed and velocity
Copy and complete the following table:
Quantity Symbol Unit Symbol Equation
Speed
Distance
Time

2. Quantity Symbol Unit Symbol Equation
Speed v
metre per
second
m/s v=d/t
Distance d metre m d=vt
Time t second s t=d/v

3. speed 
distance
time

4. Definition
• Speed is the rate of change of distance
speed 
distance
time

5. t
v 
d

7. mg 
Gm1m2
Why I don’t like formula triangles
r2
Now stick that in a triangle…

8. Can you calculate speed?
• Usain Bolt can run 100 m in 9.58 second.
How fast does he run?

9. Worked example
9.58s
v 10.44 m/s OR ms-1
t
v 
100m
d 100m
t  9.58s
v  ?
v 
d

10. Two types of speed
• How fast was Usain Bolt running at the
start?
• How fast was he running in the middle?
• How fast was he running at the finish?

11. Average speed
averagespeed 
total distance travelled
total time taken

12. Instantaneous speed
• This is the speed at
any given moment (or
instant!)
• A speedometer in a
car gives the
instantaneous speed
but you would have to
calculate the average
speed (most GPS
systems can do this
for you)

13. Displacement
• The difference between the starting point and
finishing point. It is distance with direction

14. How far does a football travel
during a match?
• Distance: many kilometers
• Displacement: 0

15. Velocity
• The rate of change of displacement
• OR
• How fast you are going in a particular
direction

16. Velocity
t
v 
s

19. February 16, 2011
Graphing movement

20. Learning objective
• Draw and interpret distance-time graphs
• Draw and interpret velocity-time graphs

21. Define these terms…
• Distance
• Displacement
• Speed
• Velocity

22. The Moving Man

31. To do
• Using graph paper draw a distance-time
graph of your journey to school
• Now try a velocity-time graph of the same
journey