1. ### Pressure Waves in an Open Tube

1. Problem Statement: The pressure in an gas tube of length L stretched along the x-axis is given by P(x, t) = Patm + P1(x, t) + P2(x, t) (1) where , P1(x, t) = 20 [P a] sin (−5.9 x − 1300 t ) P2(x, t) = 20 [P a] sin (5.9 x − 1300 t ) One open end of the air tube is at x = 0m. By how much...
2. ### What do wave crests indicate about a boat's speed?

Homework Statement *I cannot place the original image due to copyright reasons, but the image above is a good alternative. "Wave crests spread out behind a boat as shown above. What do the wave crests indicate about the boat's speed?" It is increasing. It is less than the speed of the water...
3. ### B What constitutes a closed end in acoustic resonance in tubes

Dear all, For my students, I'm currently trying out some experiments they can do to simulate acoustic processes. One of the topics that we will be discussing is that of standing waves. Although I have never done it before--I come from a completely different background--I want to create...
4. ### I Why do Harmonics Decay Faster than the Fundamental?

When looking at the FFT spectrum of a sonometer, I noticed that the harmonics decayed faster than the fundamental. Why is this?
5. ### I Y-intercept of a lambda square VS tension of standing wave

Hi all! I am doing an experiment where we create a standing wave by attaching a string to a hanging mass at one end and to a string vibrator at the other (the string passes through a pulley). When plotting the graph, the slope is inevitably 1/(u*f^2) where u is the linear density and f the...
6. S

### Standing Waves (Instruments) & Interference interpretation?

Hi, I'm trying to solve two problems related to standing waves and wave interference; while I'm not having difficulty with the actual solving portion, I don't know if I'm interpreting the questions correctly. Question 1: "A violin string is tuned to 460 Hz (fundamental frequency). When...
7. ### I Dielectrics and standing waves

How do dielectrics affect the number of modes for standing electromagnetic waves in a box?
8. Y

### B Is this an accurate description of standing waves?

Hi all, is my description below a reasonable attempt in explaining how a standing wave forms? The main part I am a bit confused as to how to explain is why the antinodes move up and down. Thanks! A standing wave is formed when energy of a wave of the right frequency is trapped in the system...
9. ### Standing Waves: Synchronization between a Tube & a Stick

Homework Statement A wooden stick, part of a musical instrument, which produces a musical sound when hit, oscillates by creating a transverse standing wave, with three antinodes and two nodes (3 "valleys", 2 "ground levels"). The lowest note has a frequency of f = 87.0 Hz, and is produced by...
10. ### Phase difference and Standing waves vs Progressive waves

and Homework Statement Ok, so I am doing As physics at the moment and have been left confused by stationary waves. I have read that between adjacent nodes/ even numbers the phase difference is always 0 and between numbers of does it is pi radians. So in the attatched image why is my textbook...
11. ### Flute player initial frequency?

Homework Statement A flute player hears four beats per second when she compares her note to a 587 Hz tuning fork (the note D). She can match the frequency of the tuning fork by pulling out the "tuning joint" to lengthen her flute slightly. What was her initial frequency? Homework Equations Not...
12. ### Python Wave on string: How can I create a traveling triangle pulse?

I have the following program that moves a wave on a string with fixed ends. The program solves the wave equation given a initial condition wave. The initial condition is a triangle wave splitting into two pulses. Here is the code written in Python: from numpy import * from matplotlib.pyplot...
13. ### I Why plucking of string creates two pulses?

When we pluck a string and a triangle is formed. Why does this triangle form into two opposite moving pulses? If we have reflective edges the two pulses will reflect, invert and superposition into the same triangle wave on the under side of the string. Let's say we have no dampening. I think...
14. ### Number of Different resonances in a closed Box

Homework Statement Show that the possible resonance frequencies in a 3D box with side a are constant multiples of ##(l^2+m^2+n^2)^{1/2}##, where l, m and n are integers. Assume that the box with sides a is filled with a gas in which the speed of sound is constant. Hence show that the number of...
15. ### B Moving to a higher harmonic in a standing wave

Imagine that you have plucked a string and it is vibrating as a standing wave at its fundamental tone (frequency f1). You leave it there and later on come back with the intention of bringing it up to the second tone (frequency f2). What should you do? It seems obvious: apply a stimulous...
16. ### I Macroscopic versus microscopic standing waves

I have read the description of electrons as standing waves based on an analogy with a string vibrating at its natural frequencies: thus the different quantum levels are akin to the tones or harmonics of the string, right? So far, so good, but then I have seen contradictory complementary views...
17. ### I Pressure standing wave nodes at the end of the open side of

I do not understand why standing sound waves can be formed in a one-side or two-side open tube. Consider a one-side open tube. In particular how does the reflection of the wave at the open end occur? I found the following explanation. I do not get why the pressure at the open end cannot vary...
18. ### I Mechanical energy in an harmonic wave and in normal modes

I think I miss something about energy of a mechanical wave. In absence of dissipation the mechanical energy transported by an harmonic wave is constant. $$E=\frac{1}{2} A^2 \omega^2 m$$ But, while studying normal modes on a rope, I find that the mechanical energy of a normal mode (still...
19. ### B Confusion with Waves

Hi everyone. I'm currently studying waves in physics at the moment but I'm super confused and hoping someone could help me clear up some things. Firstly I'll post what I think it correct (I know it's wrong) and hopefully someone could pick up exactly where I am getting confused. Waves are a...
20. ### A Reducing standing waves with phase randomization

Will constantly randomizing the phase of an audio signal, say a speaker in the corner of a square room, reduce standing waves (i.e. room modes) in the room? For example if you wanted to create a diffuse field in a small (i.e. no standing wave interference patterns) at low frequencies.
21. ### I Frequencies of standing waves in a straw

I am a physics teacher and I my class is currently studying sound waves. I had my class make some noise makers with straws as shown here. http://www.physics.org/interact/physics-to-go/straw-oboes/ We measured the frequencies coming from the straws and they seem to act like a pipe open at...
22. ### Finding the value of g using 2nd Harmonic Frequency

Homework Statement As the captain of the scientific team sent to Planet Physics, one of your tasks is to measure g. You have a long, thin wire labeled 1.80 g/m and a 1.30 kg weight. You have your accurate space cadet chronometer but, unfortunately, you seem to have forgotten a meter stick...
23. ### Find the Minimum Length of a Vibrating String

Homework Statement the equation of a stationary wave produced on a string whose both ends are fixed is given by y= [0.6sin(pi/10)x]cos(600pi)t what could be the smallest length of string? Homework Equations k=2pi/wavelength The Attempt at a Solution i got the wavelength to be 20 but don't...
24. ### Reflection of Waves and Formation of Standing Waves

I have three doubts in regard to waves on a string which I will try to make as clear as possible. For this purpose, I have considered a general wave: $$y_i=y_0\sin(\omega t - kx)$$ (1) If a wave pulse: $$y = y_0 e^{\frac{-1}{T^2} \left(t-\frac xv \right)^2}$$ is incident against a rigid...
25. ### No mass for mass per unit length

Homework Statement A ski gondola is connected to the top of a hill by a steel cable of length L and radius R . As the gondola comes to the end of its run, it bumps into the terminal and sends a wave pulse along the cable. It is observed that it took T seconds for the pulse to return. What is...
26. ### Goniometers and Standing Waves

Homework Statement Initially your receiver is positioned at a distance of 8.4 cm from the goniometer and recording a maximum intensity. You move it through 10 minimums in the intensity and then stop at the next maximum intensity. The receiver is now a distance of 27.3 cm from the goniometer...
27. ### Superposition: Adding two waves together -- amplitude help

Homework Statement " Two traveling waves are generated on the same taut string. Individually, the two traveling waves can be described by the following two equations: If both of the above traveling waves exist on the string at the same time, what is the maximum positive displacement that a...
28. ### Sound standing waves paradox...

If you seal a loudspeaker at the end of a tube and close the other end of the tube you will get standing waves; but what are the boundary conditions at the speaker for the sound pressure wave? Pressure =0 or Pressure = MAX? I find no mention of this in the literature. To find out I performed a...
29. ### Question about intensity of EM waves

For electromagnetic wave if it's reflected from a perfect conductor standing wave can be form. I wonder why Poynting vector can be used to describe the intensity of standing EM wave. (see p.19 of http://web.mit.edu/viz/EM/visualizations/coursenotes/modules/guide13.pdf ). From some textbooks...
30. ### Standing waves in tube closed tube

Homework Statement A tone with frequency 2,00 * 10^3 Hz is held above a tube filled with water. The water level is increased and decreased. When the water level is 5.7cm below the opening of the tube, the first sound maxima is heard. When the water level is 39.3cm below the opening of the...