Students use the CBR 2™ to gather distance and time data for various walking speeds. They observe the effect of change in direction and speed of motion on distance versus time graphs. Students interpret and analyze graphs, calculate slope and relate rate of change to slope.

Set up CBR 2 to take readings during each of the four trials

In the first trial, start at the 0.5 meter mark and walk away from the CBR unit at a steady slow speed

In the second trial, walk away from the CBR unit at a steady moderate speed

Plot distance-time graphs and calculate the slopes

Distance-time plots for the two trials have a positive slope, the slope for trial 2 is larger than for trial 1

In the third trial, start at the 4.5 meter mark and walk slowly towards the CBR 2 and in the fourth trial, walk with moderate speed

Sketch distance-time plots of each trial and find the slopes

Distance-time plots for the two trials have a negative slope, the slope for trial 4 is larger than for trial 3

Change in the speed of the walker, changes the size of the slope and change in the direction of the walker, changes the sign of the slope.

Predict the motion plot that will appear for a person standing still; for a person moving away quickly for a few seconds, stopping for a few seconds, then moving toward the CBR 2 slowly

TI-Navigator activity:

Use the Activity Center and have the student send in lines for different walking situations

After the Activity

Students analyze the results and answer the questions in the worksheet

Review student results:

Discuss the difference between the size (magnitude) and the sign of the slope