Activity Overview
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.
Before the Activity
Connect CBR 2 to the calculator.
Set up the CBR 2 on a desk so that it is aimed above the waist of each person walking
Launch the CBR/CBL™ App
Measure distances of 0.5 meters and 4.5 meters on the floor and mark them with masking tape
See the attached PDF file for detailed instructions for this activity
Print pages 23 - 24 from the attached PDF file for your class
Set up the TI-Navigator™ system
During the Activity
Distribute the pages to your class.
Follow the Activity procedures:
Collect Data:
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
Re-teach concepts as necessary