Texas Instruments CBR 2 Activity 2-Matchthe Graph, Notes for Teachers, Concepts, Materials, Hints

Activity 2—Match the Graph Notes for Teachers

Concepts

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

Ÿcalculator (see page 2 for available models)

ŸCBR 2™ motion detector

Ÿunit-to-CBR 2™ or I/O unit-to-unit cable

ŸEasyData 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

Distance vs. Time Matching Distance vs. Time

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.

14 GETTING STARTED WITH THE CBR 2™ SONIC MOTION DETECTOR © 2004 TEXAS INSTRUMENTS INCORPORATED