Collecting Your Own Data
Using the Texas Instrument CBL, or "calculator-based laboratory,"
you can collect your own data for a wide variety
of experiments exploring motion. The CBL works together with
the Texas Instrument TI-82, TI-85/CBL or TI-92 graphics calculators and,
via the TI-Graph Link, with either Macintosh or IBM compatible computers.
The picture below shows a simple set-up for collecting motion data --
a motion detector is connected to the TI-CBL which is, in turn, connected to
a TI-82. We plan to drop a pillow on the the motion detector. This set-up was
used to collect the sample set of data in this module. You can use the
same programs and ideas to collect other data involving motion.
The motion detector is poorly named. It is actually a distance detector,
essentially the same unit found on Polaroid cameras, that measures distance
using sonar. It emits a sound pulse and waits for an echo returning from a
target. Then it divides the time required for the echo to return by the speed
of sound to get the round trip distance to the target. It divides the round
trip distance by two to compute the one-way distance. It works for fairly
large targets at distances of roughly 1.5 feet to 30 feet. The interval
between distance measurements is limited by the time required for sound to
make the round trip.
The procedure is as follows.
- Connect the CBL, motion detector, and either a TI-92, TI-85/CBL,
or a TI-82 as shown in the figure.
- Run the TI-85/CBL
program
FALL ,
run the TI-82 program
FALL
or the TI-92 program Fall. To run the TI-92 program
type fall() amd then press ENTER from the home screen.
These programs are listed below.
If you have the TI-Graph Link program and cable and your browser has been
set up to use TI-Graph Link then you can click on the button next to the program
to see the program and then you can
download the
TI-85/CBL program to the TI-85/CBL,
download the
TI-82 program to the TI-82,
or
download the TI-92 program to the TI-92. The
program will prompt you for the time between measurements and the number of
measurements.
- When your are ready to begin measurements press the
TRIGGER key on the CBL to begin data collection. The TI-CBL will
immediately begin data collection, so you should start the motion that you
want to measure immediately after pressing the TRIGGER key.
- When data collection is complete press the ENTER key on your
calculator. You can analyze the data on the calculator or you can upload it via
TI-Graph Link to an IBM compatible or Macintosh personal computer for analysis.
TI-82 Program FALL
TI-85 Program FALL
TI-92 Program Fall
Copyright c 1995 by
Frank Wattenberg, Department of Mathematics, Carroll College,
Helena, MT 59625