Assingment 12

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course PHY 232

If your solution to stated problem does not match the given solution, you should self-critique per instructions at

http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm.

Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase

interpretation of the problem along with a statement of what you do or do not understand about it. This

response should be given, based on the work you did in completing the assignment, before you look at the

given solution.

012. `Query 10

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Question: `q**** Query introductory set six, problems 11-13 **** given the length of a string how do we

determine the wavelengths of the first few harmonics?

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Your Solution:

When given the length of a string we can calculate the wavelengths of the first few harmonics as follows;

For 1 :1 1/2 lambda=L which is equal to lambda=2L

"" 2 ;2 1/2 lambda=L which is equal to lambda=L

confidence rating #$&*:

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Given Solution: `q** As wavelength decreases you can fit more half-waves onto the string. You can fit one

half-wave, or 2 half-waves, or 3, etc..

So you get

1 half-wavelength = string length, or wavelength = 2 * string length; using `lambda to stand for wavelength

and L for string length this would be

1 * 1/2 `lambda = L so `lambda = 2 L.

For 2 wavelengths fit into the string you get

2 * 1/2 `lambda = L so `lambda = L.

For 3 wavelengths you get

3 * 1/2 `lambda = L so `lambda = 2/3 L; etc.

Your wavelengths are therefore 2L, L, 2/3 L, 1/2 L, etc..

FOR A STRING FREE AT ONE END:

The wavelengths of the first few harmonics are found by the node - antinode distance between the ends. The

first node corresponds to 1/4 wavelength. The second harmonic is from node to antinode to node to antinode,

or 4/3. the third and fourth harmonics would therefore be 5/4 and 7/4 respectively. **

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Self-critique (if necessary):

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Self-critique Rating:ok

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Question: `q**** Given the wavelengths of the first few harmonics and the velocity of a wave disturbance in

the string, how do we determine the frequencies of the first few harmonics?

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Your solution:

when given the wavelength and velocity we can easily determine the frequency of the hamornic

by rearranging this equation lambda=velocity/frequency so solving for frequecny = velocity/lambda

confidence rating #$&*:

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Given Solution:

`a** The frequency is the number of crests passing per unit of time.

We can imagine a 1-second chunk of the wave divided into segments each equal to the wavelength. The number

of peaks is equal to the length of the entire chunk divided by the length of a 1-wavelength segment. This

is the number of peaks passing per second.

So frequency is equal to the wave velocity divided by the wavelength. **

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Self-critique (if necessary):

Took a different approach but same idea

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Self-critique Rating:ok

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Question: `q **** Given the tension and mass density of a string how do we determine the velocity of the

wave in the string?

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Your solution:

Since we are given the tension and mass density we can easily find the velocity by using this

equation v=sqrt(Tension/mass density)

confidence rating #$&*:

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Given Solution:

`a** We divide tension by mass per unit length:

v = sqrt ( tension / (mass/length) ). **

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Self-critique (if necessary):

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Self-critique Rating:Ok

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Question: `q**** gen phy explain in your own words the meaning of the principal of superposition

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Your solution:

Superposition are two different waves that come together to form one wave that can be seen

confidence rating #$&*:

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Given Solution:

`a** the principle of superposition tells us that when two different waveforms meet, or are present in a

medium, the displacements of the two waveforms are added at each point to create the waveform that will be

seen. **

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Self-critique (if necessary):

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Self-critique Rating:Ok

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Question: `q **** gen phy what does it mean to say that the angle of reflection is equal to the angle of

incidence?

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Your solution:

Since the angle of incidence is the angle that is perpendicular to the surface and when reflected the

image is at an angle on the other side of the perpendicular surface.

confidence rating #$&*:

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Given Solution:

`a** angle of incidence with a surface is the angle with the perpendicular to that surface; when a ray

comes in at a given angle of incidence it reflects at an equal angle on the other side of that

perpendicular **

confidence rating #$&*:

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Self-critique Rating:Ok"

Self-critique (if necessary):

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Self-critique rating:

Self-critique (if necessary):

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Self-critique rating:

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&#Very good work. Let me know if you have questions. &#