Keep On Truckin’

by Nathan Cotten

Louisiana Curriculum Framework Content Strand: / Physical Science, Science as Inquiry / Grade
Level / 9
Objectives: The students will be able to:
  • use a TI 83+ Graphing Calculator, CBL 2 interface, and a Motion Detector to measure velocity
  • record data and graph results
  • determine the relationship between velocity and release point

Teacher Information

Benchmarks
SI-H-A1, A2, A3, A7, SI-H-B3, B4, PS-H-E2
/ Time Frame
This activity with assessment takes 90 minutes.
Curriculum Integration
  • Safety
  • Scientific method
  • Laboratory procedures
  • Lab reports
Cross Curriculum Integration
  • Physics
  • Math
  • Driver’s education
/ Materials
  • CBL 2 interface
  • TI 83+ graphing calculator
  • DataMate program
  • Vernier motion detector
  • Ramp (at least 1 m)
  • Car with card attached
  • Meter stick
  • Books to support ramp
  • Masking tape
  • Large book
  • Materials for surfaces - Astroturf, carpet, sandpaper, cotton fabric, plain wood

Applications
Students can apply this activity to:
  • driving on different road surfaces
  • friction between two surfaces
  • velocity of moving objects
/ Student Groupings
Students will be cooperatively grouped into 7 groups. Each group will have no more than 4 students each. Each student is assigned a role: Captain, Co-Captain, Materials Manager, and Recorder.
Possible Obstacles to Student Learning
  • prior knowledge of velocity
  • use of technology
  • measurement skills
  • graphing skills

Opportunities for Assessment
  • Individual laboratory reports
  • Post laboratory questions
  • Test questions: students are required to manipulate technology in a laboratory practicum.
  • Mid-term and/or Final Exam

Lesson Procedure
Keep on Truckin’
Velocity is a rate that tells how much distance is covered in a unit of time. It can be expressed by the formula
v = d/t
where v = velocity or speed (in m/s), d = distance traveled (in meters), and t = time (in sec). In this activity, you will study the velocity of a car traveling over various surfaces after it is released from a certain point on a ramp. A Motion Detector will be used to measure velocity.

Figure 1
HYPOTHESIS
1. Predict which surface will allow the car to travel the most efficient (fastest) down the ramp. Rank in order of fastest to slowest.
______
Fastest Slowest
PROCEDURE
1. Set up a ramp on books as shown in Figure 1. The high end of the ramp should be 10 cm from the floor. Place a large book on the floor 1 m from the bottom end of ramp. This book will stop your car after it comes from the ramp.
2. Attach the Motion Detector upright at the top and center of the ramp.
3. Tape a card to the back of a car. The card serves as an ultrasound reflector.
4. Connect the Vernier Motion Detector to the DIG/SONIC port of the CBL2 interface. Use the link cable to connect the interface to the TI Graphing Calculator. Firmly press in the cable ends.
5. Turn on the calculator and start the DATAMATE program by pressing APPS. Select DATAMATE by pressing 4. Press to reset the program. (DATAMATE automatically sets up the motion detector sensor).
6. Setup the graph type by pressing 1 from the menu. Press to arrow down to MODE and press .
7. Select TIME GRAPH by pressing 2. Select CHANGE TIME SETTINGS by pressing 2 again.
8. Enter 0.2 as the time between samples in seconds. Enter 15 as the number of samples.
9. Select OK by pressing 1. Select OK again by pressing 1.
10. Place your car on the ramp with its front at the 1 m line. Select START to begin collecting data by pressing 2. Release the cart after the CBL2 beeps.
Note: The Motion Detector starts to click. Get your hand out of the Motion Detector’s path quickly. Stay clear of the area in front of the Motion Detector while the green light is flashing.
11. Determine the car’s velocity.

  1. To see your velocity graph, press to select DIG-VELOCITY and press. If the displayed graph is not smooth (only one crest), press and redo the trial. Select MAIN SCREEN by pressing 1 and return to step 10.
  2. 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 below the graph. The highest point on the graph corresponds to the maximum velocity of the car. Record this maximum velocity in your data table. Round to the nearest 0.01 m/s. (In the example to the right, the maximum velocity is 1.45m/s.)
9.Do two more trials with the same surface.
  1. Press , then select MAIN SCREEN by pressing 1.
  2. Repeat Steps 10-11 two more times for a total of three trials.
10.Repeat Steps 6-9 for each surface provided by your instructor.
DATA
Data Table 1: Velocity of an Object on Various Surfaces
Surface / Trial 1 (m/s) / Trial 2 (m/s) / Trial 3 (m/s) / Average (m/s)
1.
2.
3.
4.
5.
6.
7.
Attachments
Attachment 1. Lab Report Rubric
Attachment 2. Teachers Notes
Exploration and Extension
PROCESSING THE DATA
1.Calculate the average velocity for each ramp surface. Show your work below. Enter values in Data Table 1: Velocity of an Object on Various Surfaces
1) ______m/s2) ______m/s 3) ______m/s
4) ______m/s5) ______m/s 6) ______m/s
7) ______m/s
2.Construct a bar graph of the results on the graph paper provided. Plot SURFACE TYPE on the horizontal axis and VELOCITY (in m/s) on the vertical axis.
3.Compare the velocity of the car traveling on different surfaces. Include the most and least efficient surfaces. Compare these results to your hypothesis.
4. Why do the different surfaces cause the car to travel at various speeds?
5.Describe two ways you could make the car go down the ramp faster without changing the surface of the ramp or the release position.
6.Give two reasons why road surfaces are not made of the most efficient material(s) used in this experiment.
EXTENSIONS
1.Convert the Question 1 velocities to km/h and mi/h.
2. Calculate the acceleration of the car on each surface
3.Test the velocity of the car at different release points on the ramp.
4.Design an investigation to test the effect of streamlining on the velocity of a car traveling down a ramp.
5.Test the effect of placing weights at different positions on the car.
6. Have students graph data using Graphical Analysis for Windows

Attachment 1. Lab Report Rubric

Attachment 2. Teacher's Notes

Teacher’s Notes

  • Boxes can be substituted for the books.

Make sure the Motion Detector is positioned at least 45 cm from the car. The area in front of the Motion Detector must be free of obstacles (and students).

  • ISCS cars or other skate-wheel cars work well. Toy cars with free-rolling wheels also work well. If small toy cars are used, you may want to tape two meter stick to a ramp and run the cars between them.
  • If you use longer cars (or shorter ramps), you may find it necessary to change the release positions.
  • Standard 7.5 cm x 12.5 cm cards (3” x 5”) can be attached to the cars.
  • The graph can be done by hand or using Vernier Graphical Analysis as mentioned in the extension.
  • Frictional effects in this experiment cause the data to differ from the theoretical V2 d relationship for a frictionless version of the experiment.

Safety should always be exercised in every experiment. Have students obtain and wear goggles.

References

Volz, Donald, Sapatka, Sandy. (1998) Physical Science with Calculators, “Experiment 36”, pages 36-1 through 36-2T.