What is a Wave? Start-Up: Stretch your Slinky out to a length of 12ft (12 floor tiles ), with one person at each end.

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1 What is a Wave? Name: Date: Problem: What is a Wave? Procedure Part With your partner obtain a Slinky and answer all of the question in parts 1-4. Part 5 2. With your Partner log onto the following website or log on to Mr. Skoldberg s webpage. 3. Answer questions 9-15 using the above website. Please be gentle with the Slinky s. They are easily tangled and mangled. DO NOT overstretch the Slinkys; they will become permanently deformed. Return them to their container when you are finished with the lab. Start-Up: Stretch your Slinky out to a length of 12ft (12 floor tiles ), with one person at each end. Part 1: Longitudinal (compressional) Waves With your free hand, grasp the Slinky about the last 10 coils from the end. Pull the Slinky straight back towards the end of the spring, compressing the spring. Then release the Slinky, being careful not to let go of the end of the Slinky. 1. Describe in words and drawings what you see after releasing the Slinky. 2. What happens to the wave when it reaches the other end of the Slinky? 3. From your observations what number of coils produces the best longitudinal wave? Explain. 1

2 Part 2: Transverse Waves Move your hand very quickly and sharply to the right and then back to its original position (about one tile). Practice until you can produce a single large pulse that travels down only one side of the Slinky. 4. Describe in words and drawings what you see after generating the wave. 5. Describe in words and drawings what happens to the wave when it reaches the other end of the Slinky. 6. Does the size of the wave change as it travels along the Slinky? Describe both its amplitude and its wavelength. Part 3: Interference of Transverse Waves In this section, you will be observing what happens when two transverse wave pulses meet each other. Move back to 12 tiles apart. The two people holding the ends of the spring will both send a single wave pulse at the same time, and you should observe what happens when the two waves meet in the middle. 7. If the two wave pulses are on the same side of the spring, what happens when the two waves meet in the middle of the spring? Describe in words and drawings. (It may be easier to see what is happening if you make the amplitude of one of the waves bigger than the other.) 2

3 8. If the two wave pulses are on opposite sides of the spring, describe in words and drawings what happens when they meet in the middle of the spring? Part 4: Periodic Transverse Waves So far, you ve just been sending single wave pulses down the spring. By vibrating your hand steadily back and forth, you can produce a stream of wave pulses, called a periodic wave. Try producing a periodic wave by vibrating your hand back and forth six or eight times (if you do it more you may get interference from waves reflecting off the stationary end of the spring). 9. Vary the rate at which you vibrate your hand; in other words, try shaking your hand back and forth slowly and then more quickly. How does the length of the waves that you produce depend on how fast you are vibrating your hand? Describe using words and pictures. Part 5: After logging on to the website answer to following questions below. 10. Draw a wave form and label the parts. (Including: trough, crest, wavelength, and wave height) 3

4 11. What happens to the wave when you decrease the wave height? Increase the wave height? Explain. 12. What happens to the wave when you decrease the wavelength? Increase the wavelength? Explain 13. What happens to the wave when you decrease the wave period? Increase the wave period? Explain. 14. What do you have to do to the wave height, wavelength and wave period to make the flattest wave? 15. What do you have to do to the wave height, wavelength and wave period to make the bumpiest wave? 4

5 16. Can you model a typical surface wave on the simulation? Explain how or why not. Analysis: After your investigation of waves, in your own words define the following words. Transverse Wave: Longitudinal Wave: Crest: Trough: Wavelength: After completing the lab read pages 4-9, and fill in the blanks below. Wave: EX: A boat or docks bob up and down. Most waves transfer energy by the vibration of particles in a. A is a substance through 5

6 which a wave can. A medium can be a solid, a liquid, or a. When a particle vibrates (moves back and forth, it can pass its to a particle next to it. The second particle will vibrate like the first particle does. In this way, energy is transmitted through a medium. Waves that need a medium are called (Ex Sound Waves (through the air), waves (water) Guitar and cello strings when they vibrate. Some waves can transfer energy without going through a medium. These waves are called. EX Visible Light, microwaves made by microwave ovens,, and X rays used by dentists and doctors. Although electromagnetic waves do not need a medium, they can go through matter, such as air, water, and glass. Transverse Waves: Waves in which the particles vibrate in an or Moving Across. Longitudinal Wave: the particles of the medium vibrate along the path that the wave moves. When waves move near the surface between 2 a surface wave can form. A bottle floating in the ocean is an example. How do you think surface waves are formed in the ocean? 6

7 Photo copy concept map from book Wave types and their motion through space Wave Mechanical wave Electromagnetic Wave Transverse Wave Longitudinal wave Surface Wave Transverse Wave 7