Using a simulation, apply the scientific method to investigate the various properties of transverse waves. Before attempting the activity, review the topic in Chapter 6 of Completing the reading is important for you to be able to correctly apply the properties of waves to the experiments performed in this activity. 1. After completing the background reading for this assignment, go to the Wave on a String simulation on the PhET simulations website at . Click the arrow on the simulation graphic to run the web-based simulation or click to run the simulation locally on your device. 2. Get oriented to the simulation by exploring and manipulating all the possible variables and options: a. : . In and modes, you can pause/play, step, and also change other settings regarding the wave characteristics i. 0 to 1.25 cm ii. 0 to 3.00 Hz iii. None to Lots iv. Low to gh b. : , , or c. Display (box checked) or not (box unchecked). When displayed, you will see two rulers: one horizontal and one vertical. d. display (box checked) or not (box unchecked); start/pause/reset e. dashed line that can be used as a reference for amplitude measurements Note: The rulers, timer, and reference line can all be dragged around as needed. In addition to the reference line, there is another dashed line parallel to the undisturbed string that is fixed (not moveable). f. button: starts the simulation over for the current settings g. button (circular button with a circular arrow, on the lower right of the screen): resets the simulation to the default settings h. ( ): simulation is running when this is showing; press to pause the simulation i. ( ): simulation is paused when this is showing; press to run the simulation While getting oriented with the simulation, think about how the different wave properties discussed in Chapter 6 are being illustrated in the simulation, and how changing things in the simulation affects the wave properties. 3. After spending some time experimenting with the simulation, follow the steps below to conduct four experiments. In this experiment, you will investigate and observe the properties of waves by manipulating a string attached to an energy source. Before completing the experiment, based on your current understanding after reading the background information for the activity, that makes specific predictions for how the string will react to changes to the energy source and to changes to the end of the string. 1. Click the button. The will be set to . Set the to . 2. a. Set the End to Wiggle the wrench up and down at varying speeds and over various distance ranges. As the wrench is wiggled, a wave disturbance is created and the string to moving up and down represents energy being propagated the string. Observe how the properties (wavelength, frequency, and speed) of the wave produced changes with the different wiggle action. b. After wiggling for several seconds, let go of the wrench and observe what happens. c. Click Change the End to . Wiggle the wrench as in part a. Observe the differences in the properties of the waves produced with the Loose End compared to No End. After wiggling for a bit, let go of the wrench and observe what happens. d. Click Change the End to . Wiggle the wrench as in part a. Observe the differences in the properties of the waves produced with the Fixed End compared to No End and the Loose End. After wiggling for a bit, let go of the wrench and observe what happens. Answer the questions below to help you formulate some results and conclusions for this experiment. You may need to do some additional experimentation to answer the questions. 1. In part a. of the experiment: a. Based on the definitions of transverse and longitudinal waves (chapter 6), which type of wave or is being generated along the string? Explain how you determined this. b. How is the wave frequency and wavelength affected when the wrench is wiggled faster? c. How is the wave amplitude affected when the wrench is wiggled farther up and down? 2. For which end setting(s) is taking place? Explain what causes the interference. 3. For which end setting(s) does the energy propagate away from the source without returning? Explain why the energy does not return. Based on your observations while performing the experiment and your answers to the questions above, formulate some results and conclusions for how the string will react to changes to the energy source and changes to the end of the string. In this experiment, you will investigate and observe the effects of adding tension or damping to a wave. Before completing the experiment, based on your understanding after reading the background information for the activity, that makes specific predictions for how adding tension in the string, or damping the energy along the wave, will affect the amplitude, wavelength, and speed of the wave being generated by the oscillator. Click the button, and then click the button ( ) so that the arrow ( ) is showing. Set to , set to , set to , set end to , and display the You do not need to adjust the frequency and amplitude settings. For this experiment, we will be changing the and settings. a. Click the arrow. After the oscillation wheel has turned several times, gradually adjust the from to . Observe how the amplitude, wavelength, and speed of the energy propagating along the string all change as the damping is increased, using the rulers as an aid in determining the relative changes (you do not need to take any measurements). b. Repeat the setup in part 1 above. c. Click the button. After the oscillation wheel has turned several times, gradually adjust the from to . Observe how the amplitude, wavelength, and speed of the energy propagating along the string change as the tension is increased, using the rulers as an aid in determining the relative changes (you do not need to take any measurements). Based on your observations while performing the experiment, formulate some results and conclusions for how the independent changes made to the and each affect the amplitude, wavelength, and speed of the wave being generated by the oscillator. In this experiment, you will measure the wavelength of a wave produced along the string for different settings of the wave frequency. Before completing the experiment, based on your understanding after reading the background information for the activity, that makes a specific prediction for how changing the wave frequency will affect the wavelength. 1. Click the button. Set to , set to , set to set to , set the to , set the End to , and display the . For this experiment, we will be changing the setting. 2. Construct a table like the one below. Complete the following steps to complete the table. a. After observing the generated waves with the oscillation wheel turning, click the button. b. Measure the in centimeters (cm), by using the horizontal ruler to measure the horizontal distance between consecutive wave crests (highest part of the wave) between consecutive wave troughs (lowest part of the wave). Write down the wavelength value for this frequency setting in the table. c. Change the to . Repeat steps a and b. d. Change the to . Repeat steps a and b. 1.00 Hz 2.00 Hz 3.00 Hz Multiply the frequency (in Hz = 1/s) by the corresponding wavelength (in cm). Recall from chapter 6 that: Wave speed (in cm/s) = Wavelength (in cm) X Frequency (in Hz = 1/s). You should calculate the speed, about for each of the frequency settings. Explain how the data you collected in the experiment validates the relationship between wavelength and frequency for waves traveling at the same speed, as described in Chapter 6. If your data did not validate the relationship, go back and check that you performed the experiment correctly. In this experiment, you will investigate the relationship between wave frequency and wave period, by counting the number of waves passing a given point for a given time interval and performing a calculation. Before completing the experiment, based on your understanding after reading the background information for the activity, that makes specific predictions for how the period of a wave correlates to its frequency. Click the button. Set to , set to , set to ., set to , leave the on , set the END to , and both the RULERS and TIMER. For this exercise, we will be changing the Frequency setting. Construct a table like the one below. Perform the following steps to complete the table. a. With the simulation running, position the timer above the 3 cm mark on the horizontal ruler. You will be using the 3 cm mark as a reference point for counting waves passing it. With the ruler and timer in these positions, you should be able to count wave crests passing the ruler and also see the timer. Practice counting wave that pass the vertical ruler as the simulation runs. With each wave crest that passes, one cycle of the wave has passed. b. Start the timer and count the number of wave that pass the vertical ruler in . timing is not critical; just stop counting waves when the timer reaches 10 seconds. c. Repeat step b, resetting the timer after each repeat, until you are confident that you are counting the correct number of wave crests passing in 10 seconds. Record this value in the designated location in the table. d. Change the to . Repeat steps b and c. e. For each frequency setting, divide the time interval (10 seconds) by the number of wave cycles passing in 10 seconds. This calculates the amount of time in seconds that is required for each wave to pass a given point, which is defined as the wave period. Record each calculated period in its designated location in the table. In chapter 6, you learned that the wave period is equal to 1/frequency. So, the of the corresponding frequency setting (1/frequency) and the calculated period should be very close in value. 1.00 Hz 10 seconds 2.00 Hz 10 seconds Explain how the data you collected and calculations you performed in the experiment validates the relationship between wave period and wave frequency as described in Chapter 6. If your data and calculations did not validate the relationship, go back and check that you performed the experiment correctly. 1. Create a document containing a report for each experiment. Your document should contain four paragraphs, one for each experiment. a. Title each paragraph with the corresponding name for each experiment, as it is stated in the headings for the experiments above (e.g., Experiment 1: Manipulating a Wave on a String). b. For each experiment report: i. Clearly and succinctly present your hypothesis for the experiment. ii. Based on the information prompted for in the experiments and section, clearly and succinctly summarize your observations, results, and conclusions for the experiment, and include any data collected and calculations made. iii. Clearly and succinctly evaluate the correctness of your hypothesis based on the information presented in part ii above. c. Include your full name and the date you completed the activity at the top of the document. 2. Submit your document (in either
