Lesson 1

Mechanical Wave Anatomy

Stadium Waves

Have students try to make the wave in class. If the weather is nice, you can do this outside as well.

Tips:

Make sure that everyone knows when to start the wave and that they are ready to start it at the same time.
Once everyone is ready, start the wave by raising your arms and cheering! You can either run (safely) across the classroom or use an arm to indicate when each student or section should raise their arms.

SLinky Demonstrations

Transverse Waves

PXL_20230411_161510112.TS.mp4

Longitudinal Waves

PXL_20230411_161621511.TS.mp4

Longitudinal Wave Representations

Gif above is from https://www.acs.psu.edu/drussell/demos/standingwaves/standingwaves.html

Lab

The purpose of this lab is to get students familiar with wave anatomy more than anything else. It's okay if students are not very accurate with getting the speed of the waves in this lab because they will continue practicing getting wave speed in the next few days.

Encourage students to practice using the stopwatches.

Set up

The first exploration station uses the dishpan filled with ~1 inch of water.
Explorations 2 and 3 require a slinky for each group which they can use at their tables.
Students will have to rotate and share the dishpan of water.

Stopwatch Practice

Teacher notes: There is uncertainty and error using the stopwatch to measure time. Students tend to think using a stopwatch is very accurate, but this is not the case.

Encourage students to play with the stopwatch at first. Let the students try to figure out the buttons. Have each of them try to stop the stopwatch at exactly 20.00 seconds.

Materials

Recommended Group size: 3-4 students.

Materials per Student Group

Slinky (one per student group)
Stopwatches (one per student)

General Supplies

metersticks
Rulers
1 dishpan filled ~1 inch with water

SAFETY

Avoid releasing the end of the stretched spring! Slinkies are not social creatures. Don’t let them get tangled.

Exploration 1: Water Waves

The longer the wave has to travel, the easier it is to get accurate timing. When timing the speed of the wave, you can have the students time the wave and the reflection, effectively using twice the distance.

PXL_20230411_162604673.TS.mp4

Exploration 2: Transverse Waves with slinky

Students use slinkies to make transverse waves by stretching the slinky along the floor or table and shaking their hand perpendicular to the slinky.

Exploration 3: Longitudinal Waves with slinky

Students use slinkies to make longitudinal waves by stretching the slinky along the floor or table and shaking their hand parallel to the slinky.

PXL_20230411_162222730.TS.mp4

Finding the Speed Suggestions/Modifications

Exploration 1 Water waves: The longer the wave has to travel, the easier it is to get accurate timing. When timing the speed of the wave, you can have the students time the wave and the reflection, effectively using twice the distance.

Exploration 2 and 3 Slinky waves: It's recommended to stretch the slinky at least two meters. Like the water waves, you can have the students time the wave and the reflection, effectively using twice the distance.

(OPTIONAL) If you want to be super accurate, you can use a high-speed camera with the stopwatch in-frame to find the time of wave travel.

Extra time? Measure the speed of the human wave you made in class.

Check https://www.acs.psu.edu/drussell/Demos/waves-intro/waves-intro.html for animations demonstrating wave speed.

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