Catching a Wave Answer Key

WAVES KEY THIS LAB WILL COUNT AS A MAJOR GRADE!! Be very careful with the slinkys (you break or twist = -5) Name class date Station 1 - What Can a Slinky and Some Rope Tell Us About Waves? Materials per station: 1 - Slinky 1 - 6' rope Black Tape Part I 1. A wave is any disturbance that transmits energy through matter of space. There are two main types of waves listed in your book, transverse and longitudinal waves. Define and draw a picture of each one. Define Transverse Wave: A wave that vibrates up and down. compressions rarefactions Draw a Transverse Wave and Label the trough, crest, & wavelenth. Wavelength = crest Define Longitudinal Wave: A wave that vibrates back and forth. trough image taken from: Draw a Longitudinal Wave and Label a rarefaction, compression, & wavelength. Wavelength = one compressed segment to another 2. 3. 4. 5. You will hold one end of the slinky and your partner will hold the other end. Sit across the table from each other. Gently push the slinky back and forth between you. . Observe the wave and the coil with the black tape. a. Does the coil move with the wave? Waves move in the same direction as the collisions b. What type of wave is this? Longitudinal c. Give 1 example of a wave that is also this type of wave. Sound waves wavelength Part II 1. You and your partner should spread out lengthwise across the table. Each of you should be holding the rope. 2. One person will hold the rope steady. 3. The other person will try to form a wave that travels to the other person. 4. Repeat several times, observe what happens to the piece of tape. a. What direction is the piece of tape moving? Moves perpendicular to the wave motion b. Describe how the marked tape moves relative to the wave when: 1. You move the rope faster? The tape moves up and down but does not move down the length of the rope 2. You move the rope slower? The tape moves slowly up and down. c. What type of wave is this called? Transverse d. Give another example of this type of wave. Light waves, Radio, Ultraviolet, Infrared, Microwaves Station 2 - TIDAL WAVE Materials: 3 Clear plastic boxes Water Rubber mallet A tsunami is a gigantic sea wave than can wash away an entire town in just a few seconds. Where & when did the most recent one occur? December 27 2004 Tsunami's are caused by a particular type of earthquake which you are going to model today! Today you are going to demonstrate how earthquakes affect sea waves. 1. Lightly strike the mallet on the table's front edge, top and side edge (see labeled spots on table) and observe what happens to the water in the box. Draw a picture of the waves when you hit the following: a. Front edge Wave acts a lot like a longitudinal wave. The wave is somewhat dispersed. b. Side edge c. Top Wave moves towards the opposite side of the dish away from the strike. Is similar to a transverse wave. Is the strongest wave. Will look a lot like the front hit but will be higher and seem to have more force. The three directions will determine how large the sea waves will be. The front edge produces a P (primary) wave, the side strike produces and S (secondary wave) and the top strike produces an L (surface) wave. d. Which wave do you think would cause the most damage? A surface wave Part II 1. Now use the slinky to demonstrate the three types of waves. 2. One student will be the holder and the second student will be the operator. 3. To create a P wave, the operator pushes the spring directly toward the holder. a. What type of wave is this (do not put P wave!) longitudinal 4. To create an S wave, the operator waves the spring from side to side. a. What type of wave is this (do not put S wave!) transverse 5. To create an L wave, the operator lifts the spring up and snaps it down gently. 6. Which of the three waves was the biggest? L wave (surface wave) Station 3 - What is Resonance? 1. Hold the resonator at both ends and slide it back and forth across the tabletop gently. Be careful!! If you slide it too fast the dowels with break and you will lose 10 points. Each dowel will move differently depending the length and the diameter of the dowel. a. What happens to the dowels as you shake faster? The thinner dowels will move faster at lower speeds. b. What happens to the dowels as you shake them slower? The thicker dowels will move faster at higher speeds. c. Do the dowels all move at the same rate? No How does this work? When you shake the resonator, at just the right frequency, a series of small shakes adds up to one large vibration of a particular dowel (the sticks with the balls on top of them). The shaking board sets the dowel vibrating. If the next shake is timed just right to reinforce the vibration of a particular dowel, the vibration in the dowel builds up. This process of using a series of small inputs to create a large motion is known as resonance. 2. Define resonance in your own words: