1. MOTION Slide 2 Speed Slide 3 Distance/time graphs
Slide 4 Speed Questions
Slide 5 Acceleration
Slide 6 Speed/time graphs
Slide 8 Acceleration Questions

2. s-1 means “divided by seconds”
SPEED
Speed is the distance that an object travels in a period of time. d t v
The standard units are meters and seconds (and therefore meters per second). However, sometimes km/hr is more sensible.
Distance (m, km)
Time (s, hr)
Meters per second
= ms
= m/s
=ms-1
Speed (m/s, km/hr)
s-1 means “divided by seconds”
(a.k.a. velocity)
A cyclist travels 25 km in ½ an hour.
What is their speed - in kmhr-1
- in ms-1
= 25km/0.5hr = 50km/hr
= 25000m/1800s = 13m/s

3. DISTANCE/TIME GRAPHS
A car takes 1.5 minutes to travel 500m down a busy road. It stops at lights for 30 seconds, then continues on for 1 minute as it goes another 1km.
Plot this on a distance/time graph.
Distance
(km)
0.5 1
1.5
Δd = 1km
Steepest section is fastest
Using the distance/time graph:
What is the total distance traveled?
2. In what part of the trip is the car going the fastest?
3. What is the fastest speed?
= 1.5 km
Δt = 1min
= part 3
Time (min) 1 2 3
v = Δd / Δt
v = 1km/1min
v = 1000m/60s
v = 16
In a distance/time graph the slope of the line = the speed of the object.

4. SPEED QUESTIONS What would these look like on a distance/time graph?
1. stopped
2. slow
3. fast
4. accelerating
Lab Manual pg 190/1

5. change in velocity (m/s)
ACCELERATION
Acceleration is the change in speed in an object in a period of time.
Δ v a
Δ t
change in velocity (m/s)
Where do the units come from?
a = v  t
a = m/s  s
a = m/s/s
=m/s2
= ms-2
acceleration (m/s/s)
change in time (s)
It takes a cyclist 20 seconds to go from a standing start to 14m/s.
What is their acceleration?
What is 14m/s in km/hr?
a = Δv/Δt a = 14m/s / 20s a = 0.7ms-2
= 14 × 60s × 60min  1000m
= 50.4km/hr

6. SPEED/TIME GRAPHS
A runner travels at 4m/s for 10 seconds, then stops suddenly for 5 seconds, then accelerates for 5 seconds to get to 8m/s and continues for 10 seconds.
Plot this on a speed/time graph.
In a speed/time graph the slope of the line = the acceleration of the object.
Speed
(m/s) 4 8
Using the speed/time graph:
In what part of the trip is the runner going the fastest?
What is the acceleration in part 4?
= part 5
Time (sec) 10 20 30
a = Δv/Δt
a = 8m/s/5s
a = 1.6ms-2
In a speed/time graph the distance covered = the area under the graph.

7. SPEED/TIME GRAPHS Using the speed/time graph:
3. What distance is covered in part 1?
4. What is the total distance covered?
Speed
(m/s) 4 8
d = v × t
d = 4m/s × 10s
d = 40 m
Part 1 = 40m
Part 2 = 0m
Part 3 = 0m
Part 5 = v × t = 8m/s × 10 s = 80m
Part 4 = v × t ×  = 8m/s × 5s ×  = 20m
Total = =140m
Time (sec) 10 20 30

8. ACCELERATION QUESTIONS
What would these look like on a speed/time graph?
1. stopped
2. slow
3. fast
4. accelerating
Lab Manual pg 192/3, 212/3