Units of Time & Distance
Keeping in view that in a Distance-Time graph, the distance is expressed in meters and time in seconds, try to measuring a distance of 100 meters on a straight road or a path.
Covering distance in specific time
Either by yourself or someone else, try covering the measured distance by walking or cycling on the path and note the time taken to cover the distance in each case.
Make the readings
If it has taken you 75 seconds for instance to cover the distance of 100m, then by using a stop watch note the distance you cover in every 15 seconds. You may get the following results upon measuring:
Time in seconds 0 15 30 45 60 75
Distance in meters 0 20 40 60 80 100
Finding Velocity from the Graph
Upon plotting you will see that your graph is a straight line starting from the origin. Keeping in mind that the formula for calculating Speed is Distance divided by Time, so wherever you will apply the formula you will get same result that is 1.33 m/s. This is because the straight line in Distance-Time graph represents uniform speed.