Real Life Linear Graphs

Grade D

Real Life Linear Graphs

Objective: To extract data from a time graph.

Must: Be able to understand what is happening by reading the graph

Should: Be able to calculate the average speeds on a travel graph

Could: Be able to plot a linear graph given the information required

1st March 2010

Grade D

Travel Graphs

A travel graph gives information about how someone or something has travelled over a given time period. It is also called a distance–time graph.

You can find the average speed from a distance–time graph by using the formula:

average speed = total distance travelled total time taken

You always work out the distance travelled in 1 hour to get the speed in kilometres per hour (km/h) or miles per hour (mph).

Examples

If I travelled 20 miles in 30 mins, what speed was I travelling at?

If it took me 12 mins to travel 4 miles, what was my average speed?

Example

Exercise 14B, p305, Q1 – 6.

Now lets try and plot a time graph.

Paul left his house at 8am to go to work which is 20 miles away. He had to drive 5 miles at an average speed of 10 mph to get onto the motorway. Once there he drove 10 miles at 60 mph, exited the motorway and arrived at his destination 20 mins later.

• Plot the graph• How long did it take him to get to work?