We invite you to explore PBS LearningMedia™! or here.
After 2 resource views, you will be prompted to create an account.

## Origins of Wave Energy

Lesson Summary

### Overview

There are many different types of waves that propagate through space, most of which we are unable to see. Because mechanical are by definition, waves that require a medium to transmit energy, this lesson uses slinkys in order to observe the properties of the three different types of mechanical waves. Students will use the slinkys in order to simulate wave energy and measure the results using different measuring techniques.

### Objectives

• Create and observe the different types of mechanical waves through the medium of a slinky and be able to identify them.
• Observe how the same wave propagates differently depending on the medium and be able to articulate the cause for the changes.

### Suggested Time

• One to two class periods

### Materials

• large piece of butcher paper (at least two meters in length)
• pencils
• meter sticks (1 for each group)
• string
• heavy tape (duct tape)

### Before the Lesson

• Set-up one set of materials as an example to the students. Divide the students up into groups of three and distribute materials
• Familiarize yourself with the video to be shown.

### Part I: Brief Discussion

1. Assess the students' knowledge about how ocean waves are formed by asking the class: Where do waves come from? Depending on student knowledge, it is likely that you will get a variety of answers. Some may be correct, but lack fundamental details. Some students will cite sources like "boats" and "the moon." Be sure to encourage conversation and limited debate.

2. Have the students watch the video resource: Making Big Waves.

### Part II: Review of Concepts and Exercises

3. Ask the students where the energy that form the waves originates. Students should remember from the video that weather is a large factor that contributes to wave formation. Reinforce this if students do not recall.

4. Have the students break up into their groups along with the materials for each group to perform an experiment involving generating different types of waves with the slinky. Two of the students at the ends of the extended slinky will hold the slinky and induce waves with subtle motions of their hands, one at a time, while the other students make the observations. The students will create variations of longitudinal and transverse waves by using the techniques described below. Directly after generating each wave, have them answer the questions appropriate for each wave-type before moving on to the next type of wave:

### Longitudinal waves

Have the students induce a longitudinal wave by compressing (about five inches) of the end of the extended slinky and release it. This will create a longitudinal wave. Have them record their observations about the wave and experiment in order to find the answers to the following questions:

1. What happens to the wave if you stretch out the slinky more or less and induce the wave?
2. What happens to the wave at the other end of the slinky that the wave was propagated from? Does it bounce back, or just stop?
3. Compress a larger section (more than five inches) of the slinky and release it. What difference does that make in the behavior of the wave?

### Transverse waves

Now have the students induce a transverse wave in the slinky by having one of the students on the end pull the end of the slinky a few inches off from center and snap the slinky back. This will send energy down the slinky in the form of a transverse wave. Have them record their observations about the wave and experiment in order to find the answers to the following questions:

1. What happens to the wave if you stretch out the slinky more, or less and induce the wave?
2. What happens to the wave at the other end of the slinky that the wave was propagated from? Does it bounce back, or just stop?
3. What differences do you notice between the first, longitudinal wave-type of and this transverse wave-type?

### Different Mediums and Measurements

Have the students tie one of the strings given to them to the end of the slinky and hold it rather than the slinky itself. Have them induce a transverse wave.

1. What do they notice about how the wave behaves at the intersection of the string and slinky? Make sure students explain their thinking.

Next, have the students attach the two slinkies (one smaller and one larger) to each other, end-to-end, using the strong tape and stretch out the two over the butcher paper. Have the students make a mark on the butcher paper at one end. This will be the distance that the "wave propagator" will displace the slinky to induce the next transverse wave. Have the student pull the slinky to this point and then induce the wave. Have the recorder/observer make a mark after the wave has passed into the other slinky at the crest of the wave.

• What do students notice about the height of the wave before the intersection and after?
• Does the wave make it to the end of the slinky? If not where does the energy go?

Contributor:

Funder:

Funder: