Student Exploration: Waves Gizmo, Exams of Health Physics

Download Student Exploration: Waves Gizmo and more Exams Health Physics in PDF only on Docsity! THIS GIZMOS LAB SHOULD BE DONE WEDNESDAY (11/4) AND THURSDAY (11/5) TO STAY CURRENT WITH YOUR WEEKLY LEARNING PLAN. Student Exploration: Waves DIRECTIONS: FOLLOW THE INSTRUCTIONS TO GO THROUGH THE SIMULATION. RESPOND TO THE QUESTIONS AND PROMPTS IN THE ORANGE BOXES. Vocabulary: amplitude, compression, crest, frequency, linear mass density, longitudinal wave, medium, period, power, rarefaction, transverse wave, trough, wave, wavelength, wave speed Prior Knowledge Questions (Answer 1&2 BEFORE using the Gizmo.) 1. A buoy is anchored to the ocean floor. A large wave approaches the buoy. How will the buoy move as the wave goes by? 2. The two images show side views of ocean waves. How are the two sets of waves different? P a g e 1 | 13 The buoy will move because the wave will push it. The two images showing the two different sides of the ocean waves are different because the first image of the wave is higher than the second image of the ocean wave. GIZMO WARM-UP Ocean swells are an example of waves. In the Waves Gizmo, you will observe wave motion on a model of a spring. The hand can move the spring up and down or back and forth. To begin, check that the Type of wave is Transverse, Amplitude is 20.0 cm, Frequency is 0.75 Hz, Tension is 3.0 N, and Density is 1.0 kg/m. (Note: In this Gizmo, “density” refers to the linear mass density, or mass per unit length. It is measured in units of kilograms per meter.) 1. Click Play ( ) in the GIZMO. How would you describe the motion of a transverse wave? Click Pause ( ). Notice the crests (high points) and troughs (low points) of the wave. 2. Click Reset ( ). Choose the Longitudinal wave and increase the Amplitude to 20.0 cm. Click Play. How would you describe the motion of a longitudinal wave? Click Pause. Notice the compressions in the P a g e 2 | 13 Spring model moves up and down as the wave goes from left to right. B. The wave’s amplitude is equal to half of this height. What is the amplitude? 20 cm 4. Observe : Click Reset. Select Lights on and turn off Show rulers. Select Longitudinal waves. Check that the Amplitude is 10.0 cm, the Frequency is 1.00 Hz, and the Tension is 2.0 N. Set the Density to 1.0 kg/m, and click Play. A. What is the motion of the hand? The hand moves back and forth ( left and right) B. Turn the lights off. What is the motion of the green dot? Back and forth C. Follow the motion of a single compression of the wave. How does the compression move? The compression moves to the right In a longitudinal wave, the motion of the medium is parallel to the direction of the wave. So, each point of the spring moves back and forth as the wave is transmitted from left to right. 5. Measure : With the lights on, click Pause. Turn on Show rulers. A. The wavelength of a longitudinal wave is equal to the distance between two successive compressions (or rarefactions). What is this distance? -140 B. How does this compare to the wavelength of the comparable transverse The 2 wave? (See your answer to question 2C.) wavelengths are the same 6. Measure : Click Reset. The amplitude of a longitudinal wave is equal to the distance a point on the wave is displaced from its resting position. Turn off the lights. Click Play, and then click Pause. Use the horizontal ruler to measure the width of the green trace. A. What is the width of the green trace? -20 cm B. The wave’s amplitude is equal to half of this height. What is the amplitude? -10 cm 7. Calculate : Click Reset. Select Transverse waves. Select Lights on and Show grid and turn off Show rulers. Set the Frequency to 0.50 Hz. A single cycle is the time it takes the hand to move up, move down, and then back up to the starting position. Click Play, and then click Pause after exactly one cycle. (This may take a few tries.) 2 secondsA. How long does one cycle take? This is the period (T) of the wave. Activity B: (ONLVL & Pre- AP) Wave dynamics Get the Gizmo ready : ● Click Reset. Check that Transverse is selected. ● Set Amplitude to 20.0 cm, Frequency to 0.75 Hz, Tension to 3.0 N, and Density to 1.0 kg/m. QUESTION: WHAT FACTORS AFFECT THE WAVELENGTH, SPEED, AND POWER OF WAVES? 1. Record : The speed of a wave is the distance a wave pulse travels per second. The wave speed is displayed below the spring. Click Play. What is the wave speed? 2. Experiment : The wavelength and speed of a wave can be influenced by many factors. Adjust the amplitude, frequency, tension, and density as described in the table below. Then report whether this causes the wavelength and wave speed to increase or decrease. Return each variable to its original value after each experiment. Adjustment Effect on wavelength Effect on wave speed Increase amplitude None None Increase frequency decrease None B. (f) is equal to 1 divided by the period: f = Frequency is measured in hertz (Hz), where 1 Hz = 1 cycle/sec. What is the frequency of this wave? . -0.5Hz Frequenc y 173.2 cm/s 5. Compare : Click Reset. Select Longitudinal waves. Set Amplitude to 20.0 cm, Frequency to 0.60 Hz, Tension to 2.0 N, and Density to 1.0 kg/m. Click Play. A. What is the power of this longitudinal wave? B. Compare this power to the power of a transverse wave with the same settings. Does changing the type of wave affect its power? 6. Apply : Sound waves are longitudinal waves that can travel through air. Would you expect sound waves to travel faster through a low-density gas (such as helium) or a higher-density gas such as carbon dioxide? Justify your answer based on what you have learned. the density of the medium causes the speed of a wave to decrease. Therefore I would expect sound waves to travel more slowly through the high-density carbon dioxide than 7. Apply : As ocean waves approach the shore, friction with the ocean bottom causes them to slow down. If the frequency is the same, how will this affect the wavelength of the waves? Activity C: (Pre-AP ONLY) Combined waves Get the Gizmo ready : ● Click Reset. Select Combined waves. ● Set Amplitude to 10.0 cm, Frequency to 0.75 Hz, Tension to 2.0 N, and Density to 1.0 kg/m. QUESTION: WHAT DOES WAVE MOTION LOOK LIKE WHEN TRANSVERSE AND LONGITUDINAL WAVES ARE COMBINED? 1. Observe : Click Play. Observe the motions of the hand and of the green dot in the middle. A. What is the motion of the hand? The hand moves in a circle B. Deselect the Lights On checkbox. What is the motion of the green dot? The green dot moves in a circle In a combined wave, the motion of the medium is circular. So, each point of the spring moves in a circle as the wave is transmitted from left to right. if the frequency stays the same, the wavelength must decrease as the wave speed decreases, because wave speed is equal to the product of the wavelength and the frequency. through low-density helium. C. Click Pause. Compare the crests (high points) to the troughs (low points). What do you notice? The crests are slightly rounded and the troughs are slightly pointed . The coils of the spring are apart in the crests and the close together in the troughs. Combined waves, such as ocean waves, do not look exactly like transverse waves. In the Gizmo, the troughs are pointy and the crests are rounded. In the ocean, the crests are relatively pointy while the troughs are rounded. 2. Measure : Click Reset. Select Lights on and Show rulers. Set the Frequency to 1.0 Hz. Check that the Tension is 2.0 N, the Density is 1.0 kg/m, and the Amplitude is 10.0 cm. A. Measure the horizontal distance between two crests. What is this distance? -140 cm B. What is the distance between two troughs? -140 cm