The document explains the concepts of speed, velocity, acceleration, and deceleration using speed-time graphs. It differentiates between speed and velocity, highlighting that speed does not depend on direction while velocity does, and includes activities for calculating acceleration. Additionally, it provides examples of interpreting graphs to analyze motion over time.

1. 1 of 46 © Boardworks Ltd 2007

2. Grade 9 B/C
14.3 Speed Time Graphs
Date:10/06/2024

3. Starter
10/06/2024

4. Speed/Velocity- Time Graphs!

5. What’s the difference between?
Distance and displacement
Speed and velocity

6. What is speed?
Speed is a measure of how far an object moves in a given
time.
This jet is travelling at
350m/s. This means the jet
travels 350 metres every
second.
This car is travelling at 60
mph. This means the car
travels 60 miles every hour.

7. The speed of an object does not depend on the direction in
which it is travelling. The velocity of an object is the speed
and direction in which it is moving.
The car is travelling
north with a velocity of
10m/s.
How is velocity different to speed?
As the car goes round
the corner, the speed
of the car remains
constant but the
velocity changes.

8. Speed time graphs
Lesson Objectives
1. Interpret Speed–
time graphs
2. Calculate
acceleration.
10/06/2024

9. Introduction.
10/06/2024

10. The acceleration of an object is a measure of how quickly
its velocity changes.
A train accelerates in a
straight line from rest. As it
does, its velocity increases.
The brakes on this
motorcycle are causing it
to slow down. This is
negative acceleration or
deceleration.
What is acceleration?

11. © Boardworks Ltd 2003
Speed / Time graph for car
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40 45 50 55
Time / seconds
Metres/second
Car is accelerating here – the speed is increasing.
The car is going at constant speed – acceleration is zero.
The car is decelerating here – or slowing down
The car is at rest
here – with zero
speed

12. 10/06/2024
Time in Sec
Distance
in
Km
0 5 10 15 20
40
20
60
80
Time
Speed 0 5 10 15 20
2
1
3
4
Speed = Distance /time
Speed = 70/20 = 3.5
km/sec
What does this show?
Horizontal Line Shows Constant speed
3.5 x 20 = 70 Km

13. Activity 1...
10/06/2024

14. What Graphs says: Choose correct Words
10/06/2024

15. Objective 2
10/06/2024
Calculate Acceleration

16. Acceleration and deceleration
• Speed-time graphs show speed on the vertical axis and time on
the horizontal axis.
• The gradient of a speed-time graph represents acceleration.
• Acceleration represents in Metres per second square can be
written as m/s2 or ms−2.
• A negative gradient shows the rate of “slowing down” or
deceleration.
10/06/2024

17. 10/06/2024
Time (sec)
Speed
(m/sec)
0 5 10 15 20
2
1
3
4
Acceleration
Distance time graph for the cyclist.
5
6
7
The Rate of increase of speed is
the acceleration.
Acceleration = gradient =
Acceleration = = m/sec2

18. Activity 2. Calculate acceleration and deceleration
10/06/2024
Acceleration = gradient =
For Line 1
Acceleration = m/s2
For Line 2
Constant speed / acceleration =
m/s2
For Line 3
deceleration = m/s2

19. 10/06/2024
Plenary
• Summarize the Topic

20. What
happened to
the bicycle at
seconds?
What happened
to the bicycle
between and
seconds?
For how long
was the
bicycle
stationary?
For how long
was the
bicycle going
at a speed
of ?
What was the
speed of the
bicycle after
seconds?
How many times
during the
journey did the
bicycle move at
constant speed?
Speed-Time
Graphs Spider 1
The speed-time graph
shows the journey made
by a bicycle.

21. What
happened to
the bicycle at
seconds?
What happened
to the bicycle
between and
seconds?
For how long
was the
bicycle
stationary?
For how long
was the
bicycle going
at a speed
of ?
What was the
speed of the
bicycle after
seconds?
How many times
during the
journey did the
bicycle move at
constant speed?
It
stopped
suddenl
y
𝟔𝒎/𝒔
seconds
It
decelerat
ed then
stopped
times
seconds
Speed-Time
Graphs Spider 1
- Answers
The speed-time graph
shows the journey made
by a bicycle.

22. H.W. &TDN
• H.W.
• TDN: Speed Time Graph