A Wiggle in Time Extended Through Space

Students often perceive physics as an applied math course. Problem solving and number crunching tend to dominate the landscape of the course, yet there is so much more. Physics is rich with concepts and logical ideas. This lesson takes a concepts-first approach to the topic of wave motion.

Lesson Description:

This inquiry-based lesson centers on the question “What does wave motion have in common with the motion of a mass on the end of a spring?” Students use a computer-interfaced motion detector to analyze the oscillations of a mass on a spring. A graphical display of the changes in position with respect to time is generated. Students use on-screen analysis tools to measure the time for repeating cycles of vibration. Observations and data are recorded in a lab journal.

Student observations are summarized as a class. Emphasis is given to the spring vibrating up and down at a regular rate over the course of time. Spring motion is a wiggle in time.

Students then open a Web browser and inspect a Java applet representing wave motion. Students view the motion of individual particles. Each particle is wiggling in time — like a mass on a spring. The collection of particles extended across space creates the wave pattern. Students recognize a wave as a wiggle in time extended through space.

As a follow-up to this lab investigation, students are assigned readings on the topic of waves from The Physics Classroom Tutorial from Glenbrook South High School in Glenview, Ill.

Subject Area:

This lesson is designed for a high school physics course. It can easily be adapted to a middle school physical science course.

Curriculum Standards:

This lesson addresses the following National Science Education Standards:

• Students should develop an understanding of forces and motions.
• Students should develop abilities necessary to do scientific inquiry.
• Students should use technology to improve investigations.
• Students should formulate and revise scientific explanations and models using logic and evidence.

Resources:

The LabPro data collection interface and LoggerPro software are available from Vernier Software & Technology. The interface connects to the USB port of any computer. A motion detector (from Vernier) plugs into the interface to capture motion-related data. For classrooms not equipped with such technology, a simulated representation is available online at www.walter-fendt.de/ph14e/springpendulum.htm.

The Java applet used for this activity is found at: www.smgaels.org/physics/home/java/dukes_java/TabbedWaveTrans.htm.

Physics Classroom Tutorial: gbs.glenbrook.k12.il.us/Academics/gbssci/phys/Class/BBoard.html.

Grading Rubric:

Students keep records of their lab investigations in a journal. Their data, analysis and conclusions should address the question posed at the onset of the lesson: What does wave motion have in common with the motion of a mass on the end of a spring? Students are assessed based on the depth and quality of their observations and explanations.

Teaching Tips:

• Demonstrate the two types of motion. With a student holding one end of a Slinky, introduce waves into the opposite end. Set the spring oscillating at the same time. Ask students to brainstorm the commonalities.
• Finish with the following demonstration: Obtain a whiteboard marker. Holding the marker on the whiteboard, move it up and down in sync with the oscillations of a spring. The marker is wiggling in time. Then walk at a steady pace while keeping the same up and down motion of the marker. The marker traces a sinusoidal wave pattern — a wiggle in time extended through space.