Texas Instruments CBR User manual

GG
ETTINGETTING
SS
TARTED WITHTARTED WITH
CBR™CBR™
INCLUDINGINCLUDING
55
STUDENT ACTIVITIESSTUDENT ACTIVITIES

85-86
TRIGGER
CBR
)
)
)
T
EXAS
I
NSTRUMENTS
92
Calculator-Based Rangeré(CBRé) calculator-to-CBR cable
clamp 4 AA batteries
Important notice regarding book materials
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1997 Texas Instruments Incorporated. All rights reserved.
Permission is hereby granted to teachers to reprint or photocopy in
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COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 1
Table of contents
85-86
TRIGGER
CBR
)
)
)
T
EXAS
I
NSTRUMENTS
92
INTRODUCTION
What is CBR? 2
Getting started with CBR — It’s as easy as 1, 2, 3 4
Hints for effective data collection 6
Activities with teacher notes and student activity sheets
³Activity 1 — Match the graph linear 13
³Activity 2 — Toy car linear 17
³Activity 3 — Pendulum sinusoidal 21
³Activity 4 — Bouncing ball parabolic 25
³Activity 5 — Rolling ball parabolic 29
Teacher information 33
Technical information
CBR data is stored in lists 37
RANGER settings 38
Using CBR with CBL or with CBL programs 39
Programming commands 40
Service information
Batteries 42
In case of difficulty 43
TI service and warranty 44
RANGER menu map inside back cover

COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
2GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
What is CBR?
CBRCBRé (( Calculator-Based RangerCalculator-Based Rangeré ))
sonic motion detector
use with TI-82, TI-83, TI-85/CBL, TI-86, and TI-92
bring real-world data collection and analysis into the classroom
easy-to-use, self-contained
no programming required
Includes the RANGER programIncludes the RANGER program
the versatile RANGER program is one button away
MATCH and BOUNCING BALL programs are built into RANGER
primary sampling parameters are easy to set
What does CBR do?
With CBR and a TI graphing calculator, students can collect, view, and analyze motion data
without tedious measurements and manual plotting.
CBR lets students explore the mathematical and scientific relationships between distance,
velocity, acceleration, and time using data collected from activities they perform. Students
can explore math and science concepts such as:
0motion: distance, velocity, acceleration
0graphing: coordinate axes, slope, intercepts
0functions: linear, quadratic, exponential, sinusoidal
0calculus: derivatives, integrals
0statistics and data analysis: data collection methods, statistical analysis
What’s in this guide?
Getting Started with CBRéis designed to be a guide for teachers who don’t have extensive
calculator or programming experience. It includes quick-start instructions for using CBR, hints
on effective data collection, and five classroom activities to explore basic functions and
properties of motion. The activities (see pages 13–32) include:
0teacher notes for each activity, plus general teacher information
0step-by-step instructions
0a basic data collection activity appropriate for all levels
0explorations that examine the data more closely, including what-if scenarios
0suggestions for advanced topics appropriate for precalculus and calculus students
0a reproducible student activity sheet with open-ended questions appropriate for a wide
range of grade levels

COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 3
What is CBR?
(cont.)
85-86
TRIGGER
CBR
)
)
)
T
EXAS
I
NSTRUMENTS
92
CBR includes everything you need to begin classroom activities easily and quickly — just add
TI graphing calculators (and readily available props for some activities).
0sonic motion detector 0calculator-to-CBR cable 0mounting clamp
0RANGER program in the CBR 04 AA batteries 05 fun classroom activities
s
onic sensor to record up
to 200 samples per second
with a range between
0.5 meters and 6 meters
(1.5 feet and 18 feet)
pivoting head to aim
s
ensor accurately
buttons to transfer
RANGER program to
calculators
¤button
to initiate sampling
s
tandard threaded socket
to attach a tripod or the
included mounting clamp
(on back)
battery door
(on bottom)
port to connect to CBL
(if desired)
port to connect to TI graphing
calculators using the included
2.25-meter (7.5-foot) cable
red light to indicate
s
pecial conditions
g
reen light to indicate when
data collection is occurring
(sound also available)

COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
4GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Getting started with CBR—It’s as easy as 1, 2, 3
With CBR, you’re just three simple steps from the first data sample!
Connect
Connect CBR to a TI graphing calculator
using the calculator-to-CBR cable.
Push in firmly at both ends to make the
connection.
Note: The short calculator-to-calculator
cable that comes with the calculator also
works.
Transfer
RANGER, a customized program for each calculator, is in the CBR. It’s easy to
transfer the appropriate program from the CBR to a calculator.
First, prepare the calculator to receive the program (see keystrokes below).
TI-82 or TI-83 TI-85/CBL or TI-86 TI-92
Ÿ[LINK] £›Ÿ[LINK] ¡Go to the Home screen.
Next, open the pivoting head on the CBR, and then press the appropriate
program-transfer button on the CBR.
During transfer, the calculator displays RECEIVING (except TI-92). When the
transfer is complete, the green light on CBR flashes once, CBR beeps once,
and the calculator screen displays DONE. If there is a problem, the red light
on CBR flashes twice and CBR beeps twice.
Once you’ve transferred the RANGER program from CBR to a calculator, you
won’t need to transfer it to that calculator again unless you delete it from
the calculator’s memory.
Note: The program and data require approximately 17,500 bytes of memory.
You may need to delete programs and data from the calculator. You can
save the programs and data first by transferring them to a computer using
TI-Graph Linkéor to another calculator using a calculator-to-calculator cable
or the calculator-to-CBR cable (see calculator guidebook).
2
1

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 5
Getting started with CBR—It’s as easy as 1, 2, 3
(cont.)
Run
Run the RANGER program (see keystrokes below).
TI-82 or TI-83 TI-85/CBL or TI-86 TI-92
Press ^.
Choose RANGER.
Press ›.
Press ^A.
Choose RANGER.
Press ›.
Press L[VAR-LINK].
Choose RANGER.
Press ¨›.
The opening screen is displayed.
Press ›. The MAIN MENU is displayed.
MAIN MENU
SETUPàSAMPLE
SET DEFAULTS
APPLICATIONS
PLOT MENU
TOOLS
QUIT
&view/change the settings before sampling
&change the settings to the default settings
&DISTANCE MATCH, VELOCITY MATCH, BALL BOUNCE
&plot options
&GET CBR DATA, GET CALC DATA, STATUS, STOPàCLEAR
From the MAIN MENU choose SET DEFAULTS. The SETUP screen is displayed.
Press ›to choose START NOW. Set up the activity, and then press ›to
begin data collection. It’s that easy!
Important information
0This guide applies to all TI graphing calculators that can be used with CBR,
so you may find that some of the menu names do not match exactly those
on your calculator.
0When setting up activities, ensure that the CBR is securely anchored and
that the cord cannot be tripped over.
0Always exit the RANGER program using the QUIT option. The RANGER
program performs a proper shutdown of CBR when you choose QUIT. This
ensures that CBR is properly initialized for the next time you use it.
0Always disconnect CBR from the calculator before storing it.
3
For quick results, try
one of the classroom-
ready activities in this
guide!

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6GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Hints for effective data collection
Getting better samples
How does CBR work?
Understanding how a sonic motion detector works can help you get better data plots. The
motion detector sends out an ultrasonic pulse and then measures how long it takes for that
pulse to return after bouncing off the closest object.
CBR, like any sonic motion detector, measures the time interval between transmitting the
ultrasonic pulse and the first returned echo, but CBR has a built-in microprocessor that does
much more. When the data is collected, CBR calculates the distance of the object from the
CBR using a speed-of-sound calculation. Then it computes the first and second derivatives of
the distance data with respect to time to obtain velocity and acceleration data. It stores
these measurements in lists L1, L2, L3, and L4.
Performing the same calculations as CBR is an interesting classroom activity.
➊Collect sample data in REALTIME=NO mode. Exit the RANGER program.
➋Use the sample times in L1 in conjunction with the distance data in L2 to calculate the
velocity of the object at each sample time. Then compare the results to the velocity data
in L3.
(L2n+1 + L2n)à2 N(L2n+ L2n-1)à2
L3n=
L1n+1 NL1n
➌Use the velocity data in L3 (or the student-calculated values) in conjunction with the
sample times in L1 to calculate the acceleration of the object at each sample time. Then
compare the results to the acceleration data in L4.
Object size
Using a small object at a far distance from the CBR decreases the chances of an accurate
reading. For example, at 5 meters, you are much more likely to detect a soccer ball than a
ping-pong ball.
Minimum range
When the CBR sends out a pulse, the pulse hits the object, bounces back, and is received by
the CBR. If an object is closer than 0.5 meters (1.5 feet), consecutive pulses may overlap and
be misidentified by CBR. The plot would be inaccurate, so position CBR at least 0.5 meters
away from the object.
Maximum range
As the pulse travels through the air, it loses its strength. After about 12 meters (6 meters on
the trip to the object and 6 meters on the trip back to the CBR), the return echo may be too
weak to be reliably detected by the CBR. This limits the typical reliably effective distance from
the CBR to the object to less than 6 meters (19 feet).

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 7
Hints for effective data collection
(cont.)
The clear zone
The path of the CBR beam is not a narrow, pencil-like beam, but fans out in all directions up
to 10° in a cone-shaped beam.
To avoid interference from other objects in the vicinity, try to establish a clear zone in the
path of the CBR beam. This helps ensure that objects other than the target do not get
recorded by CBR. CBR records the closest object in the clear zone.
Reflective surfaces
Some surfaces reflect pulses better than others. For example, you might see better results
with a relatively hard, smooth surfaced ball than with a tennis ball. Conversely, samples
taken in a room filled with hard, reflective surfaces are more likely to show stray data points.
Measurements of irregular surfaces (such as a toy car or a student holding a calculator while
walking) may appear uneven.
A Distance-Time plot of a nonmoving object may have small differences in the calculated
distance values. If any of these values map to a different pixel, the expected flat line may
show occasional blips. The Velocity-Time plot may appear even more jagged, because the
change in distance between any two points over time is, by definition, velocity. You may
wish to apply an appropriate degree of smoothing to the data.

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8GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Hints for effective data collection
(cont.)
RANGER settings
Sample times
TIME is the total time in seconds to complete all sampling. Enter an integer between 1
second (for fast moving objects) and 99 seconds (for slow moving objects). For
REALTIME=YES, TIME is always 15 seconds.
When TIME is a lower number, the object must be closer to the CBR. For example, when
TIME=1 SECOND, the object can be no more than 1.75 meters (5.5 feet) from the CBR.
Starting and stopping
The SETUP screen in the RANGER program provides several options for starting and stopping
sampling.
0BEGIN ON: [ENTER]. Starts sampling with the calculator’s ›key when the person
initiating the sampling is closest to the calculator.
0BEGIN ON: [TRIGGER]. Starts and stops sampling with the CBR ¤button when the
person initiating the sampling is closest to the CBR.
In this option, you also can choose to detach the CBR. This lets you set up the sample,
disconnect the cord from the CBR, take the CBR where the action is, press ¤,
sample, reattach the CBR, and press ›to transfer the data. Use BEGIN ON: [TRIGGER]
when the cord is not long enough or would interfere with data collection. This is not
available in REALTIME=YES mode (such as the MATCH application).
0BEGIN ON: DELAY. Starts sampling after a 10-second delay from the time you press ›.
It is especially useful when only one person is doing an activity.
Trigger button
The effect of ¤varies depending on the settings.
0¤starts sampling, even if BEGIN ON: [ENTER] or BEGIN ON: DELAY is selected. It also
stops sampling, but usually you will want to let a sample complete.
0In REALTIME=NO, after sampling has stopped, ¤automatically repeats the most
recent sample, but does not transfer the data to the calculator. To transfer this data, from
the MAIN MENU choose TOOLS, and then choose GET CBR DATA. (You also can repeat a
sample by choosing REPEAT SAMPLE from the PLOT MENU or START NOW from the SETUP
screen.)

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 9
Hints for effective data collection
(cont.)
Smoothing
Smoothing capabilities built into the RANGER program can reduce the effect of stray signals
or variations in the distance measurements. Avoid excessive smoothing. Begin with no
smoothing or LIGHT smoothing. Increase the degree of smoothing until you obtain
satisfactory results.
0For an activity with a higher-than-average likelihood of stray signals, you may wish to
increase the smoothing on the SETUP screen before sampling (see page 38).
0For already-collected REALTIME=NO data, you can apply smoothing to the data. The
calculator must be connected to the CBR. Choose PLOT TOOLS from the PLOT MENU,
choose SMOOTH DATA, and then choose the degree of smoothing.
Noise—what is it and how do you get rid of it?
When the CBR receives signals reflected from objects other than the primary target, the plot
shows erratic data points (noise spikes) that do not conform to the general pattern of the
plot. To minimize noise:
0Make sure the CBR is pointed directly at the target. Try adjusting the sensor head while
viewing a REALTIME=YES sample until you get good results before collecting a
REALTIME=NO sample.
0Try to sample in a clutter-free space (see the clear zone drawing on page 7).
0Choose a larger, more reflective object or move the object closer to the CBR (but farther
than 0.5 meters).
0When using more than one CBR in a room, one group should complete a sample before
the next group begins their sample.
0For a noisy REALTIME=YES sample, repeat using a higher degree of smoothing until you
obtain satisfactory results. (You cannot change the smoothing in the DISTANCE MATCH,
VELOCITY MATCH, or BALL BOUNCE applications.)
0For a noisy REALTIME=NO sample, you can apply a higher degree of smoothing to the
original data.
Speed of sound
The approximate distance to the object is calculated by assuming a nominal speed of sound.
However, actual speed of sound varies with several factors, most notably the air
temperature. For relative-motion activities, this factor is not important. For activities
requiring highly accurate measurements, a programming command can be used to specify
the ambient temperature (see pages 40–41).

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10 GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Hints for effective data collection
(cont.)
REALTIME=YES
Use REALTIME=YES mode:
0for slower objects
0to see the results as they are collected
0when you need to collect or plot only one type of data (distance, velocity, or acceleration)
for a sample
In REALTIME=YES mode, the CBR processes the requested plot data (distance, velocity, or
acceleration), which is transferred to the calculator following each individual distance
measurement. Then RANGER plots a single pixel for that pulse.
Because all of these operations must be completed before the next sample can be
requested, the maximum rate at which data can be sampled in REALTIME=YES mode is
limited.
It takes approximately 0.080 seconds just to sample, process, and transfer the data for a
single data point. Additional time is required for operations such as plotting the point, which
slows the effective sample rate to approximately 0.125 seconds in RANGER.
REALTIME=NO
Use REALTIME=NO mode:
0for faster objects
0when smoothing is required (see page 9)
0to operate the CBR in detached mode (see page 11)
0when you need to collect or plot all types of data (distance, velocity, and acceleration) for
a sample
In REALTIME=NO mode, data is stored in the CBR and not transferred to the calculator until
after all sampling is completed. The sample rate can be as fast as once every 0.005 seconds
for close objects. Data for time, distance, velocity, and acceleration is transferred to the
calculator.
Because the data is stored in the CBR, you can transfer it from the CBR to a calculator again
and again.
0Each time you change smoothing, the CBR applies the new smoothing factor, transfers
the adjusted data to the calculator, and stores the smoothed values in the lists.
0Choosing a domain changes the lists stored in the calculator. If you need to, you can
recover the original data from the CBR. From the MAIN MENU in the RANGER program,
choose TOOLS. From the TOOLS menu, choose GET CBR DATA.
0You also can share the same data with many students, even if they are using different
types of TI graphing calculators. This allows all students to participate in data analysis
activities using the same data (see page 11).

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 11
Hints for effective data collection
(cont.)
Using CBR in detached mode
Because the CBR cannot send data to the calculator immediately in detached mode, certain
settings are required. On the SETUP screen:
0Set REALTIME=NO.
0Set BEGIN ON=[TRIGGER].
The RANGER program prompts you when to detach the CBR and when to reattach it. No
special procedures are required.
Sharing data
What if you want the entire class to analyze the same data at the same time? With CBR you
can disseminate REALTIME=NO data quickly within a classroom.
➊Transfer the RANGER program to all students’ calculators prior to data collection.
➋Collect the data with the CBR in REALTIME=NO mode.
➌Have the first student attach his or her calculator to the CBR using either the calculator-
to-CBR cable or the calculator-to-calculator cable.
➍From the MAIN MENU in the RANGER program, choose TOOLS. From the TOOLS menu,
choose GET CBR DATA. TRANSFERRING... is displayed and the plot appears.
➎Press ›to return to the PLOT MENU, and then choose QUIT. Detach the cable.
➏Connect another calculator (of the same type) to the calculator with the data. On the
receiving calculator, from the MAIN MENU in the RANGER program, choose TOOLS. From
the TOOLS menu, choose GET CALC DATA. Instructions are displayed telling you how to
set the sending calculator. When it is ready, press ›, and lists L1, L2, L3, L4, and L5
are transferred automatically.
➐Transfer the data to another student’s calculator from CBR while other students
continue the calculator-to-calculator transfers.
Once all students have the same data, they can analyze the data in RANGER using the PLOT
MENU or outside RANGER using the calculator’s list and graphing features.
To share data on the TI-85, use the LINK feature outside of RANGER to transfer the lists.

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12 GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Hints for effective data collection
(cont.)
Beyond simple data collection
Once you’ve collected and plotted data in RANGER, you can explore the data in relationship
to a function. Because the data is collected as lists and displayed as a statistical plot, you can
use , , and œto explore this relationship.
Inside RANGER
0Explore plots using TRACE, which is set automatically. (On the TI-85, use the free-moving
cursor.)
0Manipulate the data set, including smoothing the data or selecting the domain of
interest.
Outside RANGER
0Explore data using the calculator’s list editor.
0Manually model a function to the data using the calculator’s Y= editor.
0Automatically determine the equation that best fits the data using the calculator’s
regression capabilities.
Other relationships can be explored beyond those represented by the plot options in
RANGER. For instance, simultaneous plots of Distance-Time and Velocity-Time can be viewed
as statistical plots. From the MAIN MENU in the RANGER program, choose QUIT, and then set
Plot1 as L1 versus L2 and Plot2 as L1 versus L3. (You may also need to adjust the Window.)
Data and plots can be sent to a computer using TI-Graph Link. This is especially useful when
students generate more involved reports of their activity findings.
Using CBR without the RANGER program
You can use CBR as a sonic motion detector with CBL or with programs other than RANGER.
0For information on using CBR with CBL, see page 39.
0For information on obtaining programs and activities, see page 36.
0For information on programming commands to write your own programs, see pages
40–41.

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 13
Activity 1—Match the graph notes for teachers
Concepts
Function explored: linear.
MATCH introduces the real-world concepts of distance
and time—or more precisely, the concept of distance
versus time. As students attempt to duplicate graphs
by walking while seeing their motion plotted, the
concept of position can be explored.
In Explorations, students are asked to convert their
rate of walking in meters per second to kilometers per
hours.
Once they have mastered the Distance-Time match,
challenge your students to a Velocity-Time match.
Materials
Ÿcalculator
ŸCBR
Ÿcalculator-to-calculator cable
A TI ViewScreenéallows other students to watch—
and provides much of the fun of this activity.
Hints
Students really enjoy this activity. Plan adequate time
because everybody will want to try it!
This activity works best when the student who is
walking (and the entire class) can view his or her
motion projected on a wall or screen using the TI
ViewScreen.
Guide the students to walk in-line with the CBR; they
sometimes try to walk sideways (perpendicular to the
line to the CBR) or even to jump up!
Instructions suggest that the activity be done in
meters, which matches the questions on the student
activity sheet.
See pages 6–12 for hints on effective data collection.
Typical plots
Typical answers
1. time (from start of sample); seconds; 1 second;
distance (from the CBR to the object); meters;
1 meter
2. the y-intercept represents the starting distance
3. varies by student
4. backward (increase the distance between the CBR
and the object)
5. forward (decrease the distance between the CBR
and the object)
6. stand still; zero slope requires no change in y
(distance)
7. varies by graph; @yà3.3
8. varies by graph; @yà1
9. the segment with the greatest slope (positive or
negative)
10. this is a trick question—the flat segment, because
you don’t move at all!
11. walking speed; when to change direction and/or
speed
12. speed (or velocity)
13. varies by graph (example: 1.5 meters in 3 seconds)
14. varies by graph; example: 0.5 metersà1 second
example: (0.5 meters à1 second) Q(60 seconds à
1 minute) = 30 meters àminute
example: (30 meters à1 minute) Q(60 minutes à1
hour) = 1800 meters àhour
example: (1800 meters à1 hour) Q(1 kilometer à
1000 meter) = .18 kilometers àhour.
Have students compare this last number to the
velocity of a vehicle, say 96 kilometers àhour
(60 miles per hour).
15. varies by graph; sum of the @y for each line
segment.

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14 GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Activity 1—Match the graph linear
Data collection
➊Hold the CBR in one hand, and the calculator in the other. Aim the sensor directly at a
wall.
Hints: The maximum distance of any graph is 4 meters (12 feet) from the CBR. The
minimum range is 0.5 meters (1.5 feet). Make sure that there is nothing in the clear
zone (see page 7).
➋Run the RANGER program (see page 5 for keystrokes for each calculator).
➌From the MAIN MENU choose APPLICATIONS. Choose METERS.
➍From the APPLICATIONS menu choose DISTANCE MATCH. General instructions are
displayed. DISTANCE MATCH automatically takes care of the settings.
➎Press ›to display the graph to match. Take a moment to study the graph. Answer
questions 1 and 2 on the activity sheet.
➏Position yourself where you think the graph begins. Press ›to begin data collection.
You can hear a clicking sound and see the green light as the data is collected.
➐Walk backward and forward, and try to match the graph. Your position is plotted on
the screen.
➑When the sample is finished, examine how well your “walk” matched the graph, and
then answer question 3.
➒Press ›to display the OPTIONS menu and choose SAME MATCH. Try to improve your
walking technique, and then answer questions 4, 5, and 6.

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© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 15
Activity 1—Match the graph
(cont.)
linear
Explorations
In DISTANCE MATCH, all graphs are comprised of three straight-line segments.
➊Press ›to display the OPTIONS menu and choose NEW MATCH. Study the first
segment and answer questions 7 and 8.
➋Study the entire graph and answer questions 9 and 10.
➌Position yourself where you think the graph begins, press ›to begin data collection,
and try to match the graph.
➍When the sampling stops, answer questions 11 and 12.
➎Press ›to display the OPTIONS menu and choose NEW MATCH.
➏Study the graph and answer questions 13, 14, and 15.
➐Press ›to display the OPTIONS menu. Repeat the activity if desired, or return to the
MAIN MENU, and then choose QUIT to exit the RANGER program.
Advanced explorations
The graphs generated by DISTANCE MATCH were all straight lines. Now try VELOCITY MATCH,
in which you must match a Velocity-Time plot. This one’s tough!
MATCH is a very popular program. Additional versions that explore more complicated graphs
may be available (see page 36).

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16 GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Activity 1—Match the graph
Name ___________________________________
Data collection
1. What physical property is represented along the x-axis? _____________________________________
What are the units? How far apart are the tick marks? ________________
What physical property is represented along the y-axis? _____________________________________
What are the units? How far apart are the tick marks? ________________
2. How far from the CBR do you think you should stand to begin? ______________________________
3. Did you begin too close, too far, or just right? _____________________________________________
4. Should you walk forward or backward for a segment that slopes up? _________________________
Why? _______________________________________________________________________________
5. Should you walk forward or backward for a segment that slopes down? ______________________
Why? _______________________________________________________________________________
6. What should you do for a segment that is flat? ____________________________________________
Why? _______________________________________________________________________________
Explorations
7. If you take one step every second, how long should that step be? ____________________________
8. If, instead, you take steps of 1 meter (or 1 foot) in length, how many steps must you take? _______
9. For which segment will you have to move the fastest? ______________________________________
Why? _______________________________________________________________________________
10. For which segment will you have to move the slowest? _____________________________________
Why? _______________________________________________________________________________
11. In addition to choosing whether to move forward or backward, what other factors entered into
matching the graph exactly? ____________________________________________________________
____________________________________________________________________________________
12. What physical property does the slope, or steepness of the line segment, represent? ____________
13. For the first line segment, how many meters must you walk in how many seconds? _____________
14. Convert the value in question 13 (the velocity) to metersà1 second: ___________________________
Convert to metersàminute: _____________________________________________________________
Convert to metersàhour: _______________________________________________________________
Convert to kilometersàhour: ____________________________________________________________
15. How far did you actually walk? _________________________________________________________

COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
© 1997 TEXAS INSTRUMENTS INCORPORATED GETTING STARTED WITH CBR 17
Activity 2—Toy car notes for teachers
Concepts
Function explored: linear.
The motion of a motorized toy car is used to illustrate
the real-world concept of constant velocity.
Materials
Ÿcalculator
ŸCBR
Ÿcalculator-to-CBR cable
Ÿbattery-operated toy car
ŸTI ViewScreen (optional)
Hints
Toy cars vary greatly in size, shape, and angle of
reflection of the incident ultrasonic sound. Therefore,
the resulting plots may vary in quality. Some vehicles
may require an additional reflective surface in order to
obtain good plots. Try mounting an index card to the
vehicle to assure a good target for the sensor.
You may wish to try a variety of vehicles so the
students can explore these effects.
Toy cars that are slower (such as those designed for
younger children) are better for this activity. Look for a
car that appears to keep a constant velocity.
See pages 6–12 for hints on effective data collection.
Explorations
The slope of an object’s Distance-Time plot at any time
gives the object’s speed at that time. Thus, for an
object traveling at constant velocity, the slope of its
Distance-Time plot is constant. This is why the
Distance-Time plot exhibits a linear relationship.
If you start collecting data before the car begins
moving, you will notice the Distance-Time plot is not
linear at the beginning of the plot. Why? The car
begins at rest (v= 0). It cannot instantaneously attain
its constant velocity. Acceleration is given by:
av
t
=∆
∆
In order for the object to go instantaneously from rest
to its constant velocity, ∆t= 0. But this implies infinite
acceleration, which is not physically possible. (In fact,
by Newton’s Second Law, F= ma, an infinite
acceleration could only result from an infinite force,
which is equally impossible.) Thus we must observe the
object accelerating (increasing its speed) to its
constant velocity over a finite time period.
Typical plots
Answers to questions
1. the first or last plot; distance increases at constant
rate
2. students enter values from TRACE
3. distance values increase by a constant amount
4. velocity is rate of change for distance over time;
the values are the same for each equal time
increment
5. student should get a value similar to the values
calculated for m
similar to m
mrepresents velocity or speed of car
6. bis the y-intercept; example: y= 2x+ 0
7. varies; for example, if m= 2, distance (y) = 20
meters after 10 seconds (y= 2 Q10 + 0); for 1
minute, y= 120 meters
Advanced Explorations
The slope of a Velocity-Time plot for constant velocity
is zero. Therefore, the Acceleration-Time plot shows
a= 0 (in the ideal case) over the time period where
velocity is constant.
The resulting area is the object’s displacement (net
distance traveled) during the time interval t1to t2.
For calculus students, the displacement can be found
from:
svdt
t
t
=
∫
1
2
where sis the object’s displacement in the interval t1
to t2.

COPYING PERMITTED PROVIDED TI COPYRIGHT NOTICE IS INCLUDED
18 GETTING STARTED WITH CBR © 1997 TEXAS INSTRUMENTS INCORPORATED
Activity 2—Toy car linear
Data collection
➊Position the car at least 0.5 meters (1.5 feet) from the CBR, facing away from the CBR in
a straight line.
Hints: Aim the sensor directly at the car and make sure that there is nothing in the
clear zone (see page 7).
➋Before starting data collection, answer question 1 on the activity sheet.
➌Run the RANGER program (see page 5 for keystrokes for each calculator).
➍From the MAIN MENU choose SETUPàSAMPLE. For this activity, the settings should be:
REALTIME: NO
TIME (S): 5 SECONDS
DISPLAY: DISTANCE
BEGIN ON: [ENTER]
SMOOTHING: LIGHT
UNITS: METERS
Instructions for changing a setting are on page 38.
➎Choose START NOW.
➏Press ›when you are ready to begin. Start the car and quickly move out of the clear
zone. You can hear a clicking sound as the data is collected and the message
TRANSFERRING... is displayed on the calculator.
➐When the data collection is concluded, the calculator automatically displays a Distance-
Time plot of the collected data points.
➑Compare the plot of the data results to your prediction in answer 1 for similarities and
differences.