## Saturday, June 20, 2009

### Distance-Time Graph

My course on the school management system in Ipoh was cut short by one day coz some of the participants were called for a meeting on Friday in Kuala Lumpur. It has been a fruitful 3 days here in Ipoh learning about the new system which will be installed in the school server next week. Anyway, I'm glad to be able to continue my lesson with 5 KA on Friday coz i really need to cover a lot more chapters before the trial exam. Managed to start the topic on distance-time graph.

Introduction

Information about movement can be presented in a number of ways. Data for the total distance moved at different times during movement can be recorded in a table. Alternatively, the same information can be presented in a graph. Plotting distance against time can tell you a lot about a journey.

If something is not moving, a horizontal line is drawn on a distance-time graph (dt-graph).

Time is increasing to the right, but its distance does not change. It is stationary

If something is moving at a steady speed, it means we expect the same increase in distance in a given time:

Time is increasing to the right, and distance is increasing steadily with time. It moves at a steady speed.

Slope and the Speed

When you look at a slope of a line on a distance-time graph you may notice how slopes can be different. The slope of the line determines the speed; the higher the slope the greater the speed, but if the slope is low then the speed is low.

As you can see in the first chart, the slope is very high, this means that the car must be traveling at a great speed. In the second graph, the slope is relatively low, which means that the car is driving at a very low speed