year 8 maths

5I
Distance–time graphs
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■ To draw a graph of a journey, use time on the horizontal axis and distance on the vertical axis.
■ Graphs of distance versus time usually consist of line segments .
A distance–time graph
constant movement
Distance
Key ideas
at rest
Time
■ Each segment shows whether the object is moving or at rest.
■ The steepness of a line segment shows the speed.
■ Steeper lines show greater speed than less steep lines. Horizontal lines show that the person or
vehicle is stationary.
■ Speed = distance
time
Example 24
Reading information from a graph
This distance–time graph shows the journey of a car from one
town (A) to another (B).
a How far did the car travel?
b How long did it take the car to complete the journey?
c What was the average speed of the car?
Distance (km)
300
200
100
B
SOLUTION
EXPLANATION
a 250 km Draw an imaginary line from point B to the
vertical axis; i.e. 250 km.
b 2.5 hours
Draw an imaginary line from point B to the
horizontal axis; i.e. 2.5 hours.
c
s = d t
250 km
=
2.5 h
= 100 km/h
Speed = distance
time
Distance = 250 km
Time = 2.5 hours
A
0
1 2 3
Time (hours)
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
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