Speed Trap

Teacher Instructions

Background Information:

    This lab allows students to conceptually explore motion graphing. By producing motion at different speeds and directions the students should begin thinking about motion and words used to describe motion.
    Student's knowledge of terminology is not important prior to the lab.

Set-Up:

    The set-up of the truck and the detector will be varied by the students in order to explore different directions and different speeds. The students should record their set - up information for each of their runs.

Procedures:

    Students are to graph the motion of the truck at various speeds and in both directions. The speed of the truck is varied by removing a battery and replacing it with a "shunt". (The purpose of the shunt may require some explanation. Students generally are satisfied by calling the shunt a "spacer". It doesn't add any more energy it just fills the space left by the battery.)
    Students should describe their procedures on the student lab sheet.

Extensions / Postlab:

  • Discuss the questions raised by the students. Hopefully you can use the terminology of velocity, constant velocity and speed here. You could also introduce the concept of acceleration in terms of a changing speed or velocity here.
  • Discuss the conclusions reached by the students. They should be able to compare the speed and direction of a moving object by looking at graphs. Perhaps sketch different slopes on the board and have you students tell you about relative speeds and directions.
  • Have students try to match already produced graphs by walking in front of the motion detector. (See "Distance Match" and "Velocity Match" under the MacMotion files)

Notes:

  • The truck used for this experiment is an inexpensive battery operated truck obtained from a toy store. The trucks speed is varied by replacing a batter with a metal spacer. For C cells spacers can be made using 1" OD copper tubing cut to length with end caps on each end. For AA cells spacers can be made from the appropriate size aluminum rod. Short wires with alligator clips could also be used.
  • There are no unusual safety hazards for this lab.

Student Instructions for ULI

The Big Question:

    How is the direction of motion and the speed of motion represented on a graph?

Equipment / Materials:

  • Computer
  • ULI
  • Motion detector
  • MacMotion software
  • Battery operated toy truck

Computer Set Up

  • Connect the interface to the computer and connect the interface to a power supply.
  • Connect the Motion detector to the interface (for a Vernier ULI use Port 2.)
  • Turn on the interface and the computer.
  • Open the motion detector software ("MacMotion" for a Macintosh and Vernier equipment)
  • Set the display to show two graphs. Make one a distance vs. time graph and the other a velocity vs. time graph.

Computer Use:

  • Place the truck in front of the motion detector
  • Click the "Start" or "Collect" button. The computer will begin collecting data.
  • Start the truck to produce the graph.

Set-Up:

    The set-up of the truck and the detector will be varied in order to explore different directions and different speeds. Basically you should record the truck at various speed moving toward the detector and at various speeds moving away from the detector.

Procedures:

  • The operation of the equipment is given in the Computer Use section.
  • Graphs are produced by starting the computer and recording the motion as the truck moves away or towards the motion detector.
  • Describe the actual procedure you use on the student lab sheet.

Data / Observation:

    Sketch each of your graphs and record how the graphs were produced on the Student Observation Sheet Be careful to not record extraneous information from the graphs. (Have your teacher help you with your first few graphs.) Your description should include the direction of the truck and the number of batteries used for each run.

Calculations:

    There are no calculations for this lab.

Conclusions:

    Address these four questions about the graphical representation of motion on your lab sheet under conclusions.:

  1. How is direction represented on a distance vs. time graph?
  2. How is direction represented on a velocity vs. time graph?
  3. How is speed represented on a distance vs. time graph?
  4. How is speed represented on a velocity vs. time graph?

Questions:

    Record any questions that arose in the lab. Include any answers to the questions you may have found.

Observation Sheet Page 1

Observation Sheet Page 2

Student Instructions for LabPro

The Big Question:

    How is the direction of motion and the speed of motion represented on a graph?

Equipment / Materials:

  • Computer
  • LabPro
  • LoggerPro software
  • Motion detector
  • Battery operated toy truck

Computer Set Up

  • Connect the interface to the computer and connect the interface to a power supply.
  • Connect the Motion detector to the LabPro in the Dig/Sonic1 port.
  • Turn on the interface and the computer.
  • Open the LoggerPro software.
  • Under the Experiment menu choose Show Sensors and select the Motion Detector in the appropriate port. You should have a distance vs. time graph and a velocity vs. time graph.

Computer Use:

  • Place the truck in front of the motion detector
  • Click the Collect button. The computer will begin collecting data.
  • Start the truck to produce the graph.

Set-Up:

    The set-up of the truck and the detector will be varied in order to explore different directions and different speeds. Basically you should record the truck at various speed moving toward the detector and at various speeds moving away from the detector.

Procedures:

  • The operation of the equipment is given in the Computer Use section.
  • Graphs are produced by starting the computer and recording the motion as the truck moves away or towards the motion detector.
  • Describe the actual procedure you use on the student lab sheet.

Data / Observation:

    Sketch each of your graphs and record how the graphs were produced on the Student Observation Sheet Be careful to not record extraneous information from the graphs. (Have your teacher help you with your first few graphs.) Your description should include the direction of the truck and the number of batteries used for each run.

Calculations:

    There are no calculations for this lab.

Conclusions:

    Address these four questions about the graphical representation of motion on your lab sheet under conclusions.:

  1. How is direction represented on a distance vs. time graph?
  2. How is direction represented on a velocity vs. time graph?
  3. How is speed represented on a distance vs. time graph?
  4. How is speed represented on a velocity vs. time graph?

Questions:

    Record any questions that arose in the lab. Include any answers to the questions you may have found.

Observation Sheet Page 1

Observation Sheet Page 2

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