Wave Problems
1. A sound wave has a frequency of 262 Hz. What is the time between successive wave crests?
Period = 1/ Frequency
Period = 1 / 262 Hz
Period = .0038s 2. A sound wave produced by a clock chime 515 m away is heard 1.50 s later. The frequency of the sound
is 436 Hz. (a) What is the speed of sound in air? (b) What is the period of the sound wave?
(c) What is its wavelength?

(a) Velocity = delta distance / delta time
Velocity = 515m / 1.50s = 343.3 m/s

(b) Period = 1 / Frequency
Period = 1 / 436 Hz
Period = .00229s

(c) Velocity = Wavelength * Frequency
Velocity / Frequency = Wavelength
343.3 m/s / 436 Hz = .7874 m

http://www.cbv.ns.ca/rv/physics/Physics11/waves1.pdf
Suppose that the two speakers in the figure are separated by 2.50 m and are vibrating exactly out of phase at a frequency of 429 Hz. The speed of sound is 343 m/s. Does the observer at C observe constructive or destructive interfernce when his distance from speaker B is

Δd=(n+1/2)λ

The Δd would can be find by finding the difference between the AC and BC.

BC and AB are given and it can be seen in the pictuce that angle ABC is 90 degrees.

AC can be found using the pythagorean theorem.

AB^2 + BC^2 = AC^2

AC = 4

Δd = 4m - 2.4m = 1.6m

Now we need to find the wavelength

Velocity = Wavelength * Frequency

Wavelength = Velocity / Frequency = .800m

(Δd/λ) - .5 will determine whether or not the there is constructive or destructive interference.

(16m/.800m) - .5 = 1.5 There is destructive interference.

Website with good description and animation of constructive and dustructive interference

World War One acoustic mirror, Kilnsea, East Yorkshire, UK. Concrete mirrors like these were constructed before the invention of radar to detect the sound of approaching enemy aircraft.

The nature of waves:

- A wave is a traveling disturbance
- A wave carries energy from place to place

Mechanical Waves- require a medium to propogate

Non- Mechanical Waves- do no require a medium to propogate

Longitudinal Waves- particle motion is in the same direction as the waves motion (direction of propogation)

Transverse Waveshttp://www.revisionworld.co.uk/files/wave.jpg

-slinky

-"The Wave"

http://cubecubed.blogspot.com/

Units:

Wavelength= meters

Speed of light= 3.08*10^8 meters per second

Period= seconds

Frequency= 1/seconds= Hz

Amplitude= meters

http://en.wikibooks.org/wiki/Basic_Physics_of_Nuclear_Medicine/Sonography_&_Nuclear_Medicine

Properties of the Speed of SoundSpeed of a WavePrinciple of Super Positionhttp://www.asdlib.org/onlineArticles/ecourseware/Bullen_XRD/XRDModule_Theory_Diffraction_3_files/Interference.JPG

Two Speakers Producing the Same Sound- Δd=d2-d1=path difference between the two sound wave
- Constructive Interference in phase: Δd=nλ
- Destructive Interference in phase: Δd=(n+1/2)λ
- Constructive Interference: When the troughs and peaks of a wave line up to produce an amplified sound
- Destructive Interference: When the trough of a wave meets with the peak of another wave, sounds cancels out
- Out of phase: half a cycle off, equations for construcive interference and destructive interference are the same except switched

http://videos.howstuffworks.com/hsw/6052-exploring-sound-sound-waves-video.htmhttp://www.nwcouncil.org/LIBRARY/1998/98-3Fig4.gif

This is a picture showing an out of phase wave. The red wave is exactly 180 degrees out of phase with the blue wave.

A good video depicting the motions of a sound wave and other important qualities of a sound wave is the following:

Wave Problems

1. A sound wave has a frequency of 262 Hz. What is the time between successive wave crests?

Period = 1/ Frequency

Period = 1 / 262 Hz

Period = .0038s

2. A sound wave produced by a clock chime 515 m away is heard 1.50 s later. The frequency of the sound

is 436 Hz.

(a) What is the speed of sound in air?

(b) What is the period of the sound wave?

(c) What is its wavelength?

(a) Velocity = delta distance / delta time

Velocity = 515m / 1.50s = 343.3 m/s

(b) Period = 1 / Frequency

Period = 1 / 436 Hz

Period = .00229s

(c) Velocity = Wavelength * Frequency

Velocity / Frequency = Wavelength

343.3 m/s / 436 Hz = .7874 m

http://www.cbv.ns.ca/rv/physics/Physics11/waves1.pdf

Suppose that the two speakers in the figure are separated by 2.50 m and are vibrating exactly

out of phaseat a frequency of 429 Hz. The speed of sound is 343 m/s. Does the observer at C observe constructive or destructive interfernce when his distance from speaker B isΔd=(n+1/2)λ

Website with good description and animation of constructive and dustructive interference

http://www.physicsclassroom.com/mmedia/waves/ipl.cfm

Interesting Videos, pictures, and linksSOURCEShttp://images.google.com/imgres?imgurl=http://www.hps.cam.ac.uk/whipple/explore/images/acoustics/acoustic_mirror.jpg&imgrefurl=http://www.hps.cam.ac.uk/whipple/explore/acoustics/parabolicsoundmirrors/&usg=__MJkrU72y7So24VNLv06E27XGyLw=&h=296&w=312&sz=23&hl=en&start=1&um=1&itbs=1&tbnid=ITOlJWdjHvX8gM:&tbnh=111&tbnw=117&prev=/images%3Fq%3Dacoustic%2Bmirror%26um%3D1%26hl%3Den%26safe%3Dactive%26sa%3DN%26rlz%3D1T4GGIE_enUS337US339%26tbs%3Disch:1Image of the Acoustic Mirror