From Omilili

**Sound****waves**

As I understand it , the length of a **sound**

**wave**measured fromm crest to crest is always the same , and a reading of 60 db using a

**sound**source of 4khz would the amplitude of both

**sound**

**waves**be the... as we are talking

**about**a graphical representation of the

**sound**pressure level . A sine

**wave**, right...

From Yahoo Answers

**Question:**Ultrasound waves are used to measure blood-flow speeds. Suppose a device emits sound at 500 kHz, and the speed of sound in human tissue is taken to be 1540 m/s. What is the expected beat frequency if blood is flowing normally in large leg arteries at 3.0 cm/s directly away from the sound source? I'm stuck on this one can someone help me out? Thanks.

**Answers:**I'm not sure what the question is..."What is the expected beat frequency" that part confuses me. You already know the frequency of the emitted sound, 500 kHz, and you know the velocity of the blood flow, 3.0 cm/s. According to the Doppler equation you have everything except the Doppler angle... F = Fo (c + v cos(q))/ (c - v cos(q)) where: c is the acoustic velocity in blood, i.e., 1.54 10 5 cm/s; F o is the transmitted frequency; q is the Doppler angle; v is the velocity of the blood. Try to re-word and see what we can come up with!

**Question:**I have always wanted to ask this question, and it puzzles me because a radio wave i think always as the same wavelength so with radio caves carrying a music file and another carrying a piece of document, what is different about those to radio waves that carry the different data. And same with electricity i mean a electron is an electron so whats different about the electricity carrying sound and another line of electricity carrying an internet download.

**Answers:**Radio waves are electromagnetic radiation. It is called radiation only because it doesn't require a medium in which to travel. A changing electric field generates a changing magnetic field which generates a changing electric field which generates a changing magnetic field which generates.....you get the picture. All this propagation travels approximately 186,000 miles/sec or 300 million meters/sec. This is the speed regardless of how fast the fields change. The electric or magnetic field goes through a positive and negative change. This is called a cycle. The number of cycles per second the field goes through is called frequency measured in Hertz. The wavelength of the radio signal is inversely proportional to the frequency. Picture a 1 MHz radio signal traveling for one second. Chop up that 300 million meter long signal into 1 million parts. Each part would be a cycle 300 meters long. wavelength (in meters) = 300 / frequency (in MHz) So every frequency has a different wavelength and visa versa. Information is placed on a radio signal in two basic ways; amplitude modulation (AM) and frequency modulation (FM). Both modulate a single radio signal at a certain frequency, called a carrier. AM superimposes a voice signal onto the carrier. The amplitude of the radio frequency (RF) signal at any moment in time is the same as the signal coming from the microphone. With FM, the amplitude changes are converted into frequency changes and that is superimposed onto the carrier instead. On the receiving end, a combination of electronic coils and capacitors conduct differently to different carrier frequencies. These are tuned to pass a signal of the right frequency. The signal is then demodulated and the original voice signal recovered. This is all an over-simplification of how radio works, but it's close. Signals through wires are similar but you are only dealing with movements of electrons vs RF and changing electromagnetic waves. when those moving electrons go into an antenna, they create a changing magnetic field which creates a changing electric.......

**Question:**A jet is flying horizontally from A to B. When the plane is directly overhead at B, a person on the ground (C) hears the sound coming from A. ABC is a right triangle in B. The angle BCA = 36 degrees. The average temperature is 20 degrees Celsius. If the speed of the plane at A is 170 m/s, what is the speed at B, assuming that it has constant acceleration? - Relevant equations f=1/T f: frequency; T: period v= *f = /T : wavelength f(observer)= f(plane)*((v+v[sub]o[/sub])/(v+v[sub]p[/sub])) v=343m/s - The attempt at a solution First off I don't see what steps to take to come up with the answer. There must some implicit data to take into consideration but I can't figure it out. What I assume, since there is a right triangle with an angle given, is that one distance has to be found (AC) to find AB with sin. I found the acceleration by taking t=1second. I know that the sound travels at 343m/s on AC and the speed the plane has after one second on AB is found by calculating v[sub]plane[/sub]= sin(36)*343= 201.6m/s so the acceleration is a= (201.6-170)/1s= 31.6m/s[sup]2[/sup] I can't figure out how to get the distance from A to C or A to B. PS: those values are given from my homework given by the teacher, on the book the same problem has 164m/s for the speed of the plane at A, same angle. The answer for the speed at B is 239m/s

**Answers:**Answer for the book problem. Distance AB covered by the plane = average velocity * time AB = [v + 164]*t/2-----1 Distance AC covered by sound = velocity * time AC = 343*t-------2 1/2 gives sin 36 = [v + 164]/ [ 2*343] sin 36*686 = v+164 v = 403.22-164 v = 239.m/s ========================= sin 36 = [v + 170]/ [ 2*343] v = 403.22-170 v =233.m/s =============================

From Youtube

### Crop Circles and Sound (Part 4)

Crop Circles and Sound (Part 4) Ed Sherwood deciphers the design symbolism of the Litchfield 1995 Crop Circle pictogram and reveals another piece of evidence linking the biophysical effects of sound to non-manmade Crop Circle creation. Crop Circles & Sound: Super Enhanced Seed Growth from Inside a Non-Manmade Crop Circle Formation By Ed Sherwood In early August 1990, I discovered and amassed compelling scientific evidence that 'Sound' could be involved in the physics of non-manmade Crop Circle creation, and that sonic and ultrasonic energy might explain many of the anomalous biophysical effects observed in certain Crop Circle formations plants, seeds and soil. Turning to one of several books in my collection for example, that I had prized for many years entitled 'The Secret Life of Plants', I learned how in the mid-1960s, Mary Measures and Pearl Weinberger, of Canada's University of Ottowa, found that ultrasonic frequencies greatly affect the germination and growth of plant seeds and seedlings: 'their experiments indicated, albeit inexplicably, that the enzyme activity and respiration rates in plants and their seeds increased when they were stimulated by ultrasonic frequencies. Stored wheat exposed to high frequency waves for insect control, for example, grew faster than unexposed wheat when planted.' Noted biophysicist Dr WC Levengood stated in 'Anatomical Anomalies in Crop Formation Plants' (published in Physiologia Plantarum, Vol. 92, 1994) that, "Crop Circle energies**...**