You will plot the relation between the traveled time on the horizontal axis and the distance on the vertical axis. The results
will show you how far you are from your house with respect to time. In order to input the data, click your right mouse button on
the black background empty graphic area.
Select ‘Edit Data’ or ‘Edit Data Excel’, then the table for your data entry will pop up.
As you can see, the first column is for the Time axis, and the second column is for the Distance axis. In order to input the data,
click your left mouse button on the table.
You can move this table around with your left mouse button by dragging it. Type the distance from your house to where you are
at 100 seconds and 200 seconds.
Type your data here!
You will get this graph showing how your distance changes with the time when you move at a constant pace. As you can see,
there are two distinctive straight blue lines. From 0 to 100 seconds, it indicates that you are moving away from your home. From
100 to 200 seconds, it indicates that you are moving towards your home.
50
50
When you want to know about the velocity of this motion, you must consider it for two different cases; walking from home to
the 100 meter mark and returning from the 100 meter mark to home.
50
50
Now, let’s calculate your speed for the 0 to 100 second interval. You can choose any two time points while you’re in constant
motion. I’ll take 0s and 50s. You now find corresponding distances. They are 0 meters at 0 seconds and 50 meters at 50 seconds.
50
50
The speed or velocity is simply the slope of the(straight)line. That is the ratio between the distance changes and the time you
take to travel. So it is 50 meters divided by 50 seconds, which turns to 1 m/s.
50
50
Velocity = slope of the red straight line
= corresponding position change / any time interval
= 50 meters/ 50 seconds = 1 m/s
For the returning home case, it is a negative slope, as you can see. I will chose from 150 to 200 seconds. The corresponding
distances are 50 and 0 meters. The traveled distance decreases from 50 to 0 during the 50-second interval. That is, the velocity is
-1 m/s. For the two cases, the speed is the same, but the velocity is different.
50
50
150
Velocity = slope of the red straight line
= corresponding position change / any time interval
= -50 meters/ 50 seconds = –1 m/s