Getting Started with the CBR 2
Sonic Motion Detector
™
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Activity 1 (Graphing Your Motion) and Activity 3 (A Speedy Slide) are used with permission from Vernier Software and Technology. These
activities were adapted from Middle School Science with Calculators by Don Volz and Sandy Sapatka.
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Table of Contents
Introduction
What is the CBR 2™ Sonic Motion Detector? 2
Getting started with the CBR 2™ Sonic Motion Detector 4
Hints for effective data collection 6
Activities with teacher notes and student activity sheets
³ Activity 1 — Graphing your motion linear 10
³ Activity 2 — Match the graph linear 14
³ Activity 3 — A Speedy slide parabolic 18
³ Activity 4 — Bouncing ball parabolic 24
³ Activity 5 — Rolling ball parabolic 28
Teacher information 32
Technical information
Sonic motion detector data is stored in lists 36
EasyData settings 37
Using a CBR 2™ Sonic Motion Detector with a CBL 2™ System
or with CBL 2™ System programs 38
use with TI-83 Plus, TI-83 Plus Silver Edition,TI-84 Plus, TI-84 Plus Silver Edition
TI-92 Plus, TI-89, TI-89 Titanium, and Voyage™ 200
bring real-world data collection and analysis into the classroom
easy-to-use
What does the CBR 2™ sonic motion detector do?
With the CBR 2™ motion detector and a TI graphing calculator, students can collect, view,
and analyze motion data without tedious measurements and manual plotting.
The
CBR 2™ motion detector 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:
0 motion: distance, velocity, acceleration
0 graphing: coordinate axes, slope, intercepts
0 functions: linear, quadratic, exponential, sinusoidal
0 calculus: derivatives, integrals
0 statistics and data analysis: data collection methods, statistical analysis
0 Physics: motion, use with dynamics tracks, pendulum analysis, position, velocity,
acceleration
0 Physical Science: motion experiments
What’s in this guide?
Getting Started with the CBR 2™ Sonic Motion Detector is designed to be a guide for
teachers who do not have extensive calculator experience. It includes quick-start instructions
for using the
activities to explore basic functions and properties of motion. The activities (see pages 10–
31) include many of the following:
0 teacher notes for each activity, plus general teacher information
0 step-by-step instructions
0 a basic data collection activity appropriate for all levels
0 explorations that examine the data more closely, including what-if scenarios
0 suggestions for advanced topics appropriate for precalculus and calculus students
0 a reproducible student activity sheet with open-ended questions appropriate for a wide
range of grade levels
CBR 2™ motion detector, hints on effective data collection, and five classroom
Getting started with the CBR 2™ Sonic Motion Detector
With the CBR 2™ motion detector, you’re just two or three simple steps from the first data
sample!
1111
2222
Download
For TI-83 and TI-84 family calculator users:
Your graphing calculator may have been preloaded with a number of Apps
(software applications), including the EasyData App. Press Œ to see the
Apps installed on your calculator. If EasyData is not installed, you may find
the latest version of this App at education.ti.com. If necessary, download the
EasyData App now.
For TI-89, TI-92 Plus, TI-89 Titanium and Voyage™ 200 users:
Obtain the latest RANGER program and install it on your calculator. RANGER
cannot be installed from the
from www.vernier.com or education.ti.com.
CBR 2™ motion detector. RANGER is available
Connect
For TI-83 and TI-84 family calculator users:
Connect the
the Standard-B to Mini-A USB cable (unit-tocable, and push in firmly at both ends to make a secure connection.
CBR 2™ motion detector to your TI graphing calculator using
CBR 2™) or I/O unit-to-unit
Set the Sensitivity switch to
etc., or to Track mode for use with dynamics tracks and carts.
About the unit-to-
0 Can only be used with the EasyData App.
0 Provides for an auto-launch capability of the EasyData App when
connecting a
0 Provides for an improved physical and more reliable connection than the
I/O unit-to-unit cable.
0 Cannot be used with RANGER, DataMate, or other similar applications.
For TI-89, TI-92 Plus, TI-89 Titanium and Voyage™ 200 users:
Connect the
the I/O unit-to-unit cable and push in firmly at both ends to make a secure
connection.
Set the Sensitivity switch to
etc., or to Track mode for use with dynamics tracks and carts.
CBR 2™ cable:
CBR 2™ motion detector to a TI-84 Plus-family calculator.
CBR 2™ motion detector to your TI graphing calculator using
Quit. This ensures that the CBR 2™ motion detector is properly
CBR 2™ motion detector.
CBR 2™ motion detector when you
Hints for effective data collection
Getting better samples
How does the CBR 2™ sonic motion detector 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.
The
CBR 2™ motion detector, like any sonic motion detector, measures the time interval
between transmitting the ultrasonic pulse and the first returned echo, but the
motion detector has a built-in microprocessor that does much more. When the data is
collected, the
motion detector 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.
Object size
Using a small object at a far distance from the CBR 2™ motion detector 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.
CBR 2™ motion detector calculates the distance of the object from the CBR 2™
CBR 2™
Minimum range
When the CBR 2™ motion detector sends out a pulse, the pulse hits the object, bounces
back, and is received by the
CBR 2™ motion detector. If an object is closer than 15
centimeters (about six inches), consecutive pulses may overlap and be misidentified by the
CBR 2™ motion detector. The plot would be inaccurate, so position the CBR 2™ motion
detector at least 15 centimeters 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
return echo may be too weak to be reliably detected by the
limits the typical reliably effective distance from the
CBR 2™ motion detectorto the object to
CBR 2™ motion detector), the
CBR 2™ motion detector. This
less than 6 meters (about 20 feet).
Sensitivity switch
The sensitivity switch has two modes—Track and Normal.
The Track mode is intended for activities using dynamics
tracks and carts; the Normal mode is intended for all other
Track Normal
%&
activities, such as, walking, ball toss, bouncing ball,
pendulum, etc.
If you are getting lots of extra noise in your data, the sensitivity switch may be in the Normal
mode. Moving the sensitivity switch to the Track position, will reduce the sensitivity of the
sensor and may produce better data.
The path of the CBR 2™ motion detector beam is not a narrow, pencil-like beam, but fans
out in all directions up to 15° from center in a 30° cone-shaped beam.
To avoid interference from other objects in the vicinity, try to establish a clear zone in the
path of the
target do not get recorded by the
records the closest object in the clear zone.
Reflective surfaces
CBR 2™ motion detector beam. This helps ensure that objects other than the
CBR 2™ motion detector. The CBR 2™ motion detector
15 centimeter
(cont.)
30°
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.
EasyData settings (for TI-83, TI-83 Plus, TI-84, and TI-84 Plus users only)
Setup data collection for Time Graph
Experiment length is the total time in seconds to complete all sampling. It’s determined by
the number of samples multiplied by the sample interval.
Enter a number between 0.05 (for very fast moving objects) and 0.5 seconds (for very slow
moving objects).
Note: See “To set up the calculator for data collection” on page 12 for detailed information
about how to change settings.
Menu name Description Default setting
Sample Interval Measures time between samples in seconds. 0.05
Number of Samples Total number of samples to collect. 100
Experiment Length Length of the experiment in seconds.5
Starting and stopping
To start sampling, select Start (press q). Sampling will automatically stop when the
number of samples set in the
detector will then display a graph of the sampled data on the graphing calculator.
Time Graph Settings menu is reached. The CBR 2™ motion
To stop sampling before it automatically stops, select
Stop (press and hold q) at any time
during the sampling process. When sampling stops, a graph of the sampled data is
displayed.
Noise—what is it and how do you get rid of it?
When the CBR 2™ motion detector 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:
0 Make sure the CBR 2™ motion detector is pointed directly at the target. Try adjusting the
sensor head while viewing live data on the home-screen meter. Make sure the reading
you receive is appropriate before starting an activity or experiment.
0 Try to sample in a clutter-free space (see the clear zone drawing on page 7).
0 Choose a larger, more reflective object or move the object closer to the CBR 2™ (but
farther than 15 centimeters).
0 When using more than one CBR 2™ motion detector in a room, one group should
complete a sample before the next group begins their sample.
0 Try moving the sensitivity switch to the Track position to reduce the sensitivity of the
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.
The
CBR 2™ motion detector has a built-in temperature sensor to automatically compensate
for changes in the speed of sound due to the temperature of the surrounding air. The
temperature conversion from 0° to 40° Celsius, at standard pressure, is fairly linear at about
+0.6 meters/second per degree Celsius. The speed of sound increases from about 331
meters/second at 0° Celsius to about 355 meters/second at 40° Celsius. These speeds
assume a relative humidity of 35% (dry air).
(cont.)
When using the EasyData App with the
compensation will take place when collecting motion data. The sensor is located underneath
the holes on the back of the
not cover these holes with something that is of a different temperature from the
surrounding ambient temperature.
CBR 2™ motion detector; therefore, when collecting data, do
CBR 2™ motion detector, this temperature
Using the CBR 2™ sonic motion detector without the EasyData application
You can use the CBR 2™ unit as a sonic motion detector with a CBL 2™ system or with
programs other than EasyData.
Using the I/O unit-to-unit cable, the
calculators that do not have the EasyData App installed but do have the
the RANGER program. The
CBR™ motion detector when sample data is collected using the CBL/CBR App and/or the
RANGER program.
CBL/CBR App can be used on most older TI-83 Plus calculators. The CBL/CBR App is
The
available for downloading at education.ti.com and allows you to collect motion data using
the I/O unit-to-unit cable on the
The RANGER program, which is part of the
allows you to collect motion data using the I/O unit-to-unit cable. Many TI Explorations
workbooks use the RANGER program. (The RANGER program is the only program available
for use with the TI-89, TI-92 Plus, TI-89 Titanium, and Voyage™ 200 to perform activities
like Ball Bounce and Graph Match.)
CBR 2™ motion detector will provide the same functionality as a
CBR 2™ motion detector can be used with graphing
CBL/CBR App and/or
CBR 2™ motion detector.
CBL/CBR App and available for other calculators,
You can also use
Use the DataMate App that comes with the
detector
For more information about this cable visit the TI webstore at education.ti.com.
through a CBL 2™ system. A special CBL-to-CBR cable is required to use this system.
CBR 2™ unitas a motion sensor with your CBL 2™ data collection device.
CBL 2™ system to operate the CBR 2™ motion
Activity 1—Graphing Your Motion Notes for Teachers
Concepts
Function explored: linear
Materials
Ÿ calculator (see page 2 for available models)
Ÿ CBR 2™ motion detector
Ÿ unit-to-CBR 2™ or I/O unit-to-unit cable
Ÿ EasyData application or RANGER program
Ÿ Masking tape
Ÿ Meter stick
Hints
This experiment may be the first time your students
use the CBR 2™ motion detector. A little coaching on
its use now will save time later in the year as the
CBR 2™ motion detector is used in many experiments.
The following are hints for effective use of the
CBR 2™ motion detector:
0 In using the CBR 2™ motion detector, it is
important to realize that the ultra sound is emitted
in a cone about 30° wide. Anything within the
cone of ultrasound can cause a reflection and
possibly an accidental measurement. A common
problem in using motion detectors is getting
unintentional reflections from a desk or chair in
the room.
0 Often unintended reflections can be minimized by
tilting the CBR 2™ motion detector slightly.
0 If you begin with a velocity or acceleration graph
and obtain a confusing display, switch back to a
distance graph to see if it makes sense. If not, the
CBR 2™ motion detector may not be properly
targeting the target.
0 The CBR 2™ motion detector does not properly
detect objects closer than 15 cm. The maximum
range is about 6 m, but stray objects in the wide
detection cone can be problematic at this distance.
0 Sometimes a target may not supply a strong
reflection of the ultrasound. For example, if the
target is a person wearing a bulky sweater, the
resulting graph may be inconsistent.
0 If the velocity and acceleration graphs are noisy, try
to increase the strength of the ultrasonic reflection
from the target by increasing the target’s area.
You may want to have your students hold a large
book in front of them as they walk in front of the
CBR 2™ motion detector. This will produce better
graphs because it smoothes out the motion.
Typical plots
Distance vs. Time
Matching Distance vs. Time
Answers to questions
9. The slope of the portion of the graph
corresponding to movement is greater for the
faster trial.
Results will probably vary between groups as they
may walk at different rates.
Walking towards the motion detector will produce
a negative slope. While walking away from the
motion detector will produce a positive slope.
12. Note that the slope is close to zero (if not zero)
when standing still. The slope should be zero, but
expect small variation due to the variation in
collected data.
Function explored: linear
Distance Match introduces the real-world concepts of
distance and time—or more precisely, the concept of
distance versus time.
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
Ÿ calculator (see page 2 for available models)
Ÿ CBR 2™ motion detector
Ÿ unit-to-CBR 2™ or I/O unit-to-unit cable
Ÿ EasyData application or RANGER program
A TI ViewScreené panel allows 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
ViewScreené panel.
Guide the students to walk in-line with the CBR 2™
motion detector; they sometimes try to walk sideways
(perpendicular to the line to the CBR 2™ motion
detector) 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 6–9 for hints on effective data collection.
Typical plot
Typical answers
1. time (from start of sample); seconds; 1 second;
distance (from the CBR 2™ motion detector 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 2™ motion detector and the object)
5. forward (decrease the distance between the
CBR 2™ motion detector 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 à 1 second) Q (60 seconds à
1 minute) = 30 meters à minute
example: (30 meters à 1 minute) Q (60 minutes à 1
hour) = 1800 meters à hour
example: (1800 meters à 1 hour) Q (1 kilometer à
1000 meters) = 1.8 kilometers à hour.
Have students compare this last number to the
velocity of a vehicle, say 96 kilometers à hour
(60 miles per hour).
15. varies by graph; sum of the @y for each line
segment.
Function explored: parabolic
The motion of sliding down a playground slide is used
to illustrate the real-world concept of changing
velocity due to friction.
Materials
Ÿ calculator (see page 2 for available models)
Ÿ CBR 2™ motion detector
Ÿ unit-to-CBR 2™ or I/O unit-to-unit cable
Ÿ EasyData application or RANGER program
Ÿ Playground slide
Hints
The use of a playground area with several slides is
preferable for this experiment. The slides should be
straight. Slides with other shapes could be used in an
extension. For safety reasons, remind your students
not to attempt to pass each other while on the slide
steps.
You may wish to carry the interfaces, calculators, and
motion detectors to the playground area in a box or
boxes, and distribute the equipment to your students
there. Remind your students that the Motion Detector
does not properly detect objects closer than 15cm.
Depending on the type of slides that are available, you
may wish to change the way your students position
themselves for data collection. Some slides have large
platforms where the student with the Motion
Detector and the student with the calculator and
interface can be located.
Students can use wax paper, slippery cloth, sand, and
other materials to increase their speed. To enable your
students to be prepared, be sure to alert them to Part
II in advance.
Typical plots
A Speedy Slide
Typical answers
1. See the Sample Results.
2. In the Sample Results, the Part 2 speed was 0.90
m/sec greater than the Part 1 speed. Wax paper
was used to decrease friction and increase speed.
3. Answers will vary. Speeds will differ because of
differences such as contact area, weight,
streamlining, and the use of low-friction materials.
4. Answers will vary.
5. Increasing the height of the slide should increase
speed.
6. The stone dropped from the top of the slide
should hit the ground first because friction and the
incline of the slide slow the rolling stone more.
7. The level part at the bottom of a slide slows sliders
and prevents injuries.
Extensions
Design and carry out a plan to measure speed or
velocity on a different piece of playground equipment.
Have a contest to see who in the class or group can
obtain the greatest speed going down a slide.
You have been familiar with playgrounds and slides since you were a small child. The force of gravity pulls
you down a slide. The force of friction slows you down. In the first part of this experiment, you will use a
CBR 2™ motion detector to determine your speed or velocity going down a playground slide. In the
second part, you will experiment with different ways to increase your speed going down the slide.
Objectives
In this experiment, you will:
0 use a CBR 2™ motion detector to determine your speed going down a slide
0 experiment with ways to increase your speed going down the slide
0 explain your results
Data collection, Part 1, Sliding Speed
Ê Connect the CBR 2™ motion detector to the calculator using an appropriate cable (see
below) and firmly press in the cable ends.
0 If TI-83 Plus, TI-89, TI-92 Plus, TI-89 Titanium, Voyage™ 200, use an I/O unit-to-
unit cable
0 If TI-84 Plus, use a Standard-B to Mini-A USB cable (unit-to-CBR 2™)
Ë On the calculator, press Œ and select EasyData to launch the EasyData App or press
2° and select RANGER if you are using a calculator that does not operate
with EasyData.
a. After data collection stops and a graph of distance versus
time is displayed, select
b. Press 2 to select
c. Use ~ to examine data points along the graph. As you move the cursor right and
left, the time (X) and velocity (Y) values of each data point are displayed above the
graph. The highest point on the graph corresponds to the highest speed of the
slider. Record this highest speed in the Data table. Round to the nearest 0.01 m/s.
(In the example to the right, the highest speed is 2.00 m/s.)
Function explored: parabolic
Real-world concepts such as free-falling and bouncing
objects, gravity, and constant acceleration are
examples of parabolic functions. This activity
investigates the values of height, time, and the
coefficient A in the quadratic equation,
Y = A(X – H)
2
+ K, which describes the behavior of a
bouncing ball.
Materials
Ÿ calculator (see page 2 for available models)
Ÿ CBR 2™ motion detector
Ÿ unit-to-CBR 2™ or I/O unit-to-unit cable
Ÿ EasyData application or RANGER program
Ÿ large (9-inch) playground ball
Ÿ TI ViewScreené panel (optional)
Hints
This activity is best performed with two students, one
to hold the ball and the other to select
Start on the
calculator.
See pages 6–9 for hints on effective data collection.
The plot should look like a bouncing ball. If it does
not, repeat the sample, ensuring that the
CBR 2™
motion detector is aimed squarely at the ball. A large
ball is recommended.
Typical plot
TI-83/84 Family TI-89/Titanium/92+/V200
Explorations
After an object is released, it is acted upon only by
gravity (neglecting air resistance). So A depends on
the acceleration due to gravity, N9.8 metersàsecond
(N32 feetàsecond
2
). The negative sign indicates that
2
the acceleration is downward.
The value for A is approximately one-half the
acceleration due to gravity, or N4.9 metersàsecond
(N16 feetàsecond
2
).
2
Typical answers
1. time (from start of sample); seconds; height à
distance of the ball above the floor; meters or feet
2. initial height of the ball above the floor (the peaks
represent the maximum height of each bounce);
the floor is represented by y = 0.
3. The Distance-Time plot for this activity does not
represent the distance from the
detector to the ball.
Ball Bounce flips the distance
CBR 2™ motion
data so the plot better matches students’
perceptions of the ball’s behavior. y = 0 on the
plot is actually the point at which the ball is
farthest from the
CBR 2™ motion detector, when
the ball hits the floor.
4. Students should realize that the x-axis represents
time, not horizontal distance.
7. The graph for A = 1 is both inverted and broader
than the plot.
8. A < L1
9. parabola concave up; concave down; linear
12. same; mathematically, the coefficient A represents
the extent of curvature of the parabola; physically,
A depends upon the acceleration due to gravity,
which remains constant through all the bounces.
Advanced explorations
The rebound height of the ball (maximum height for a
given bounce) is approximated by:
y = hp
0 y is the rebound height
0 h is the height from which the ball is released
0 p is a constant that depends on physical
x
, where
characteristics of the ball and the floor surface
0 x is the bounce number
For a given ball and initial height, the rebound height
decreases exponentially for each successive bounce.
When x = 0, y = h, so the y-intercept represents the
initial release height.
Ambitious students can find the coefficients in this
equation using the collected data. Repeat the activity
for different initial heights or with a different ball or
floor surface.
After manually fitting the curve, students can use
regression analysis to find the function that best
models the data. Follow the calculator operating
procedures to perform a quadratic regression on lists
L1 and L2.
Extensions
Integrate under Velocity-Time plot, giving the
displacement (net distance traveled) for any chosen
time interval. Note the displacement is zero for any
full bounce (ball starts and finishes on floor).
Ê Begin with a test bounce. Drop the ball (do not throw it).
Hints: Position the
the height of the highest bounce. Hold the sensor directly over the ball and make sure
that there is nothing in the clear zone (see page 7).
CBR 2™ motion detector at least 0.5 meters (about 1.5 feet) above
Ë Run the EasyData application or RANGER program.
Ì EasyData Users: From the Setup menu, choose 4:Ball Bounce, and then select Start (press
q). General instructions are displayed. Ball Bounce automatically takes care of the
settings.
RANGER Users: From the Main Menu, choose 3: Applications. Choose the distance
units, then choose 3:Ball Bounce.
Í Have one person hold the calculator and CBR 2™ motion detector, while another
person holds the ball beneath the sensor.
Î Select Start (press q). When the CBR 2™ motion detector begins clicking, release the
ball, and then step back. (If the ball bounces to the side, move to keep the
motion detector directly above the ball, but be careful not to change the height of the
CBR 2™ motion detector.)
CBR 2™
Ï When the clicking stops, the collected data is transferred to the calculator and a plot of
distance vs. time is displayed.
Ð If the plot doesn’t look good, select Main, Start, Start to repeat the sample. Study the
plot. Answer questions 1 and 2 on the activity sheet.
Ñ Observe that Ball Bounce automatically flipped the distance data. Answer questions 3
The Distance-Time plot of the bounce forms a parabola.
Ê The plot is in Trace mode. Press ~ to determine the vertex of the first good bounce—a
nice shape without lots of extra noise. Answer question 5 on the activity sheet.
Ë Select Main to return to the main screen. Choose Quit, and then select OK to quit
EasyData.
Ì The vertex form of the quadratic equation, Y = A(X – H)
appropriate for this analysis. Press
any functions that are selected. Enter the vertex form of the
quadratic equation: Yn=A…(X–H)^2+K.
Note: If you have the Transformation Graphing application
installed on your calculator, this is accomplished much easier by
changing coefficient values directly on the graph screen. (There
is no Transformation Graphing application for the TI-89,
TI-89 Titanium, TI-92 Plus, or Voyageé 200.)
TI-89, TI-89 Titanium, TI-92 Plus and Voyageé 200 users enter
yn(x) = a* (x+h)^2 + k.
Parabolic
2
+ K, is
œ. In the Y= editor, turn off
TI83/84 Family
TI89/Titanium/92+/V200
Í On the Home screen, store the value you recorded in question 5 for the height in
variable K; store the corresponding time in variable H; store 1 in variable A.
For example (TI-83 & TI-84 Family users): Press 4 v t K Í, 2.5 v t
H Í, 1 v t A Í to set K=4, H=2.5, and A=1.
Tip (all users): At the beginning, you may want to increase the y max value of the
window settings in order to see the function being drawn and keep the collected data
on the same graph.
Î Press to display the graph. Answer questions 6 and 7.
Ï Try A = 2, 0, –1. Complete the first part of the chart in question 8 and answer
question 9.
Ð Choose values of your own for A until you have a good match for the plot. Record
your choices for A in the chart in question 8.
Ñ Repeat the activity, but this time choose the last (right-most) full bounce. Answer
questions 10, 11, and 12.
Advanced explorations
Ê Repeat the data collection, but do not choose a single parabola.
Ë Record the time and height for each successive bounce.
Ì Determine the ratio between the heights for each successive bounce.
Í Explain the significance, if any, of this ratio.
Function explored: parabolic
Plotting a ball rolling down a ramp of varying
inclines creates a family of curves, which can be
modeled by a series of quadratic equations. This
activity investigates the values of the coefficients in
the quadratic equation, y = ax
2
+ bx + c.
Materials
Ÿ calculator (see page 2 for available models)
Ÿ CBR 2™ motion detector
Ÿ unit-to-CBR 2™ or I/O unit-to-unit cable
Ÿ EasyData application or RANGER program
Ÿ large (9 inch) playground ball
Ÿ long ramp (at least 2 meters or 6 feet—a
lightweight board works well)
Ÿ protractor to measure angles
Ÿ books to prop up ramp
Ÿ TI ViewScreené panel (optional)
Hints
Discuss how to measure the angle of the ramp. Let
students get creative here in measuring the initial
angle. For example, they might use a trigonometric
calculation or folded paper.
For steeper angles (greater than 60º), you may
want to use a CBR 2™ motion detector clamp (sold
separately).
See pages 6–9 for hints on effective data collection.
Typical plots
7. 0¡ is flat (ball can’t roll); 90¡ is the same as a
free-falling (dropping) ball
Explorations
The motion of a body acted upon only by gravity is
a popular topic in a study of physical sciences. Such
motion is typically expressed by a particular form of
the quadratic equation,
s = ½at
0 s is the position of an object at time t
0 a is its acceleration
0 v
0 s
In the quadratic equation y = ax
y represents the distance from the
2
+ vit + si where
is its initial velocity
i
is its initial position
i
2
+ bx + c,
CBR 2™ motion
detector to the ball at time x if the ball’s initial
position was c, initial velocity was b, and
acceleration is 2a.
Advanced explorations:
Since the ball is at rest when released, b should
approach zero for each trial. c should approach the
initial distance, 0.5 meters (1.5 feet). a increases as
the angle of inclination increases.
If students model the equation y = ax
manually, you may need to provide hints for the
values of b and c. You may also direct them to
perform a quadratic regression on lists
their calculators. The ball’s acceleration is due to
the earth’s gravity. So the more the ramp points
down (the greater the angle of inclination), the
greater the value of a. Maximum a occurs for
q = 90¡, minimum for q = 0¡. In fact, a is
proportional to the sine of q.
2
+ bx + c
L1, L2 using
15¡ 30¡
Typical answers
1. the third plot
2. time; seconds; distance of object from CBR 2™
motion detector; feet or meters
3. varies (should be half of a parabola, concave
up)
4. a parabola (quadratic)
5. varies
6. varies (should be parabolic with increasing
curvature)
g. Select Next (press q) to display a summary of the new
settings.
h. Select OK (press s) to return to the main screen.
(cont.)
Í When the settings are correct, choose Start (press q) to begin sampling.
Î When the clicking begins, release the ball immediately (don’t push) and step back.
Ï When the clicking stops, the collected data is transferred to the calculator and a plot of
distance vs. time is displayed. Answer questions 2, 3, 4, and 5.
Explorations
Examine what happens for differing inclines.
Ê Predict what will happen if the incline increases. Answer question 6.
Ë Adjust the incline to 30¡. Repeat steps 2 through 6. Add this plot to the drawing in
question 6, labeled 30¡.
Parabolic
Ì Repeat steps 2 through 6 for inclines of 45¡ and 60¡ and add to the drawing.
Í Answer question 7.
Advanced explorations
Adjust the time values so that x = 0 for the initial height (the time at which the ball was
released. You can do this manually by subtracting the x value for the first point from all the
points on your plot, or you can enter
Ê Calculate the values for a, b, and c for the family of curves in the form y = ax
at 0¡, 15¡, 30¡, 45¡, 60¡, 90¡.
Ë What are the minimum and maximum values for a? Why?
Ì Write an expression describing the mathematical relationship between a and the angle
How might your classes change with a CBR 2™ sonic motion detector?
The CBR 2™ motion detector is an easy-to-use system with features that help you integrate it
into your lesson plans quickly and easily.
CBR 2™ motion detector offers significant improvements over other data-collection
The
methods you may have used in the past. This, in turn, may lead to a restructuring of how
you use class time, as your students become more enthusiastic about using real-world data.
0 You’ll find that your students feel a greater sense of ownership of the data because they
actually participate in the data-collection process rather than using data from textbooks,
periodicals, or statistical abstracts. This impresses upon them that the concepts you
explore in class are connected to the real world and aren’t just abstract ideas. But it also
means that each student will want to take his or her turn at collecting the data.
0 Data collection with CBR 2™ motion detector is considerably more effective than
creating scenarios and manually taking measurements with a ruler and stopwatch. Since
more sampling points give greater resolution and since a sonic motion detector is highly
accurate, the shape of curves is more readily apparent. You will need less time for data
collection and have more time for analysis and exploration.
0 With CBR 2™ motion detector students can explore the repeatability of observations and
variations in what-if scenarios. Such questions as “Is it the same parabola if we drop the
ball from a greater height?” and “Is the parabola the same for the first bounce as the
last bounce?” become natural and valuable extensions.
0 The power of visualization lets students quickly associate the plotted list data with the
physical properties and mathematical functions the data describes.
Other changes occur once the data from real-world events is collected.
CBR 2™ motion
detector lets your students explore underlying relationships both numerically and graphically.
Explore data graphically
Use automatically generated plots of distance, velocity, and acceleration with respect to time
for explorations such as:
0 What is the physical significance of the y-intercept? the x-intercept? the slope? the
maximum? the minimum? the derivatives? the integrals?
0 How do we recognize the function (linear, parabolic, etc.) represented by the plot?
0 How would we model the data with a representative function? What is the significance
of the various coefficients in the function (e.g., AX
Explore data numerically
2
+ BX + C)?
Your students can employ statistical methods (mean, median, mode, standard deviation,
etc.) appropriate for their level to explore the numeric data. When you exit the EasyData
application or RANGER program, a prompt reminds you of the lists in which time (L1),
distance (L2), velocity L3), and acceleration (L4) are stored.
CBR 2™ motion detector plots—connecting the physical world and mathematics
The plots created from the data collected by EasyData or RANGER are a visual representation
of the relationships between the physical and mathematical descriptions of motion. Students
should be encouraged to recognize, analyze, and discuss the shape of the plot in both
physical and mathematical terms. Additional dialog and discoveries are possible when
functions are entered in the Y= editor and displayed with the data plots.
Performing the same calculations as
activity.
1. Collect sample data. Exit the EasyData application or RANGER program.
2. Use 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.
(
L3
=
n
L2
n+1
3. Use the velocity data in
sample times in
L1 to calculate the acceleration of the object at each sample time. Then
L3 (or the student-calculated values) in conjunction with the
compare the results to the acceleration data in
0 A Distance-Time plot represents the approximate position of an object (distance from the
CBR 2™ motion detector) at each instant in time when a sample is collected. y-axis units
are meters or feet; x-axis units are seconds.
CBR 2™ motion detector is an interesting classroom
+ L2n)à2 N (L2n + L2
n-1
)à2
L1
NL1n
n+1
L4.
0 A Velocity-Time plot represents the approximate speed of an object (relative to, and in
the direction of, the
CBR 2™ motion detector) at each sample time. y-axis units are
metersàsecond or feetàsecond; x-axis units are seconds.
0 An Acceleration-Time plot represents the approximate rate of change in speed of an
object (relative to, and in the direction of, the
time. y-axis units are metersàsecond
0 The first derivative (instantaneous slope) at any point on the Distance-Time plot is the
2
or feetàsecond2; x-axis units are seconds.
CBR 2™ motion detector) at each sample
speed at that instant.
0 The first derivative (instantaneous slope) at any point on the Velocity-Time plot is the
acceleration at that instant. This is also the second derivative at any point on the
Distance-Time plot.
0 A definite integral (area between the plot and the x-axis between any two points) on the
Velocity-Time plot equals the displacement (net distance traveled) by the object during
that time interval.
0 Speed and velocity are often used interchangeably. They are different, though related,
properties. Speed is a scalar quantity; it has magnitude but no specified direction, as in
“6 feet per second.” Velocity is a vector quantity; it has a specified direction as well as
magnitude, as in “6 feet per second due North.”
A typical CBR 2™ motion detectorVelocity-Time plot actually represents speed, not
velocity. Only the magnitude (which can be positive, negative, or zero) is given. Direction
is only implied. A positive velocity value indicates movement away from the
motion detector; a negative value indicates movement toward the
detector.
The
CBR 2™ motion detector measures distance only along a line from the detector. Thus,
if an object is moving at an angle to the line, it only computes the component of velocity
parallel to this line. For example, an object moving perpendicular to the line from the
CBR 2™ motion detector shows zero velocity.
The mathematics of distance, velocity, and acceleration
The area under the Velocity-Time plot from t1 to t2 = @d = (d2Nd1) = displacement from
t
to t2 (net distance traveled).
1
t=2
So, @d = (
Web-site resources
At TI’s Web Site, education.ti.com, you will find:
0 a listing of supplemental material for use with the CBR 2™ motion detector and TI
graphing calculators
0 an activities page with applications developed and shared by teachers like you
0 CBR 2™ motion detector programs that access additional CBR 2™ motion detector
features
0 more detailed information about the CBR 2™ motion detector settings and programming
commands
v(@t)) or @d =
∑
t=1
@t
t
1t2
(cont.)
t=2
t=1
Acceleration-Time plot
v(dt)
⌠
⌡
At Vernier’s Web Site, www.vernier.com, you will find the the RANGER program.
Additional resources
Texas Instruments’ Explorations books provide supplemental material related to TI graphing
calculators, including books with classroom activities for the
appropriate for middle-school and high-school math and science classes.
Collected data is stored in lists L1, L6, L7, and L8 in EasyData
When the CBR 2™ motion detector collects data, it automatically transfers it to the calculator
and stores the data in lists. Each time you exit the EasyData App, you are reminded of where
the data is stored.
The lists are not deleted when you exit the EasyData application or RANGER program. Thus,
they are available for additional graphical, statistical, and numerical explorations and
analyses.
You can plot the lists against each other, display them in the list editor, use regression
analysis, and perform other analytical activities. For example, you could collect data from a
student walking away from the
calculator manual-fit linear regression, you could have students find a line of best fit.
EasyData Settings (TI-83 and TI-84 Family Calculators)
Changing EasyData settings
EasyData displays the most commonly used settings before data collection begins.
Ê From the main screen in the EasyData App, choose Setup > 1: Dist or 2: Time Graph.
The current settings are displayed on the calculator.
Note: Settings for
3: Distance Match and 4: Ball Bounce in the Setup menu are preset
and cannot be changed.
Ë Select Next (press q) to move to the setting you want to change. Press u to
clear a setting.
Ì Repeat to cycle through the available options. When the option is correct, select Next to
move to the next option.
Í To change a setting, enter 1 or 2 digits, and then select Next.
Î When all the settings are correct, select OK (press s) to return to the main screen.
The new settings remain in effect unless you choose to set EasyData to its default settings,
run an application, or run another activity that changes the settings. If you manipulate
outside the EasyData App or delete
L5, the default settings may be restored the next time
you run EasyData.
Restoring EasyData settings to the defaults
The default settings are appropriate for a wide variety of sampling situations. If you are
unsure of the best settings, begin with the default settings, and then adjust the settings for
your specific activity.
0 To restore the default settings in EasyData while the CBR 2™ motion detector is
connected to the calculator, choose
File > 1:New.
L5
0 To change settings, follow the steps previously described above.
0 Select Start (press q) to begin collecting data.
Using a CBR 2™ Sonic Motion Detector with a CBL 2™
System or with CBL 2™ System Programs
Î DataMate automatically identifies the CBL 2™ sensors, loads its calibration factors, and
displays the name of the sensor (Motion in this case), as well as the current distance
reading in meters. It also loads a default motion experiment of 5 seconds.
Ï Start collecting data with the default experiment.
Hold the motion sensor in your hand and choose 2: START to
begin data collection.
Ð Walk towards a wall while holding the CBR 2™ motion
detector pointed towards the wall.
When finished, your graph will be similar to the one shown
detector can run without batteries only if attached to a
Battery installation
motion detector is designed to operate with 4 AA alkaline batteries. CBR 2™ motion
CBL 2™.
Exit the EasyData application or RANGER program before
changing batteries.
1. Holding the
CBR 2™ motion detectorupside down, use
your thumb to slide the battery compartment cover
toward the back of the
CBR 2™ motion detector.
2. Position batteries according to the diagram on the inside
of the
3. Two batteries fit positive side up in the side marked +.
CBR 2™ motion detector battery compartment.
Two batteries fit negative side up in the side marked -.
4. Slide the cover back on. CBR 2™ motion detector is ready
to begin sampling.
CBR 2™ sonic motion detector low battery warnings
The CBR 2™ motion detector has two mechanisms to alert you that the batteries are low:
0 The EasyData App displays a warning message on calculator screen while trying to
collect data.
0 The red light flashes intermittently while the CBR 2™ motion detector is collecting
sample data.
You can check battery status using the RANGER program. From the Main Menu, select
5:Tools, then select 3:CBR Status. The battery status is checked and displayed on the first
line of the screen.
Battery precautions
0 DO NOT use rechargeable batteries.
0 Replace all four batteries at the same time. Do not mix brands of batteries. Do not mix
types within a battery brand.
0 Install batteries according to the diagrams inside the battery compartment.
0 Properly dispose of used batteries immediately. Do not leave them within the reach of
children.
0 Do not heat, burn, or puncture batteries. Batteries contain hazardous chemicals and may
explode or leak.
0 Do not mix rechargeable and nonrechargeable batteries.
0 Do not place nonrechargeable batteries in a battery recharger.
Difficulty collecting data Check for a poor calculator-to-CBR 2™ motion detector connection. Always push
in firmly on both ends of the cable.
Check for low batteries (see page 40).
The CBR 2™ motion detector
begins collecting data by itself
The CBR 2™ motion detector
doesn’t quit collecting data
Communication Error
Insufficient memory You must have sufficient memory for the EasyData App and the data lists.
Calculator doesn’t match activity
instructions
Data doesn’t look right:
0 points not on the curve
0 jagged plots
0 flat plots
0 broken plot
Lost unit-to-CBR 2™ cable You can use the I/O unit-to-unit cable that came with the calculator. (The unit-to-
Frequently low batteries Before storing the CBR 2™ motion detector, properly exit the EasyData App (using
If you set down the CBR 2™ motion detector with the ¤ button face down,
the ¤ button may depress and activate sampling. Press ¤ again to
stop sampling.
Before storing the
) or any other CBR 2™ motion detector or CBL 2™ system App.
Quit
CBR 2™ motion detector, properly exit the EasyData App (using
Press ¤ to stop sampling. Repeat sample. If problem continues, remove
one battery and put it back in. Note: Any data stored in the
CBR 2™ motion
detector will be lost.
Attach the CBR 2™ motion detector to the calculator with the Standard-B to Mini-
A USB cable (unit-toCheck for a poor calculator-to-
CBR 2™).
CBR 2™ motion detector connection. Always push
in firmly on both ends of the cable.
If you do not want to (or cannot) attach the
CBR ™ motion detector to the
calculator, quit the EasyData App.
EasyData needs 5000 bytes to run effectively. You need to delete items from the
calculator memory.
On the TI calculator, press y L
2:Mem Mgmt./Del. Choose items to delete
and press DEL to delete the selected items.
This guide applies to all the TI calculators that can load the EasyData App. You
may find that some of the menu names, screens, or keys in this guide do not
match exactly those on your calculator. If using Ranger, or other programs, choose
the closest match. For example, if the instructions say “Choose
on the TI-83 you would choose
DIST MATCH.
DISTANCE MATCH,”
Repeat the sample, ensuring that the CBR 2™ motion detector is aimed directly at
the object.
Read pages 6–9 on getting good data samples.
Check that the clear zone does not contain students, tables, or other objects.
Check the position of the Sensitivity switch.
When using two
CBR 2™ units at the same time in the same room, one group
should complete a sample before the next group begins their sample.
Check for a poor calculator-to-
CBR 2™ motion detector connection. Always push
in firmly on both ends of the cable.
Check for low batteries (see page 40).
CBR 2™ cable allows auto-launching of EasyData and a more reliable connection,
so you may wish to order a replacement cable.)
) or any other CBR 2™ motion detectoror CBL 2™ program, and disconnect
International Information: education.ti.com/international
For technical support
KnowledgeBase and
Support by E-mail:
Phone (not toll-free): (972) 917-8324
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Customer Support before returning a product for service.
education.ti.com/support
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education.ti.com/support
Always contact TI
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contact your local TI retailer/distributor.
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your specific requirements. All software is provided “AS IS.”
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Australia & New Zealand Customers only
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This Texas Instruments electronic product warranty extends only to the original purchaser and user of the product.
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