DULAY, Anthony Mark V. anthonydulay0431@gmail.com

E303: Kundts Tube Velocity of Sound in Solid

METHODOLOGY

Among the experiments the group already

performed, this has the shortest time to consume

and the simplest so far. Since there are only limited

Kundts Tube Apparatus from the laboratory room, the section wait for one hour before we started. And

while waiting to them, The professor give us a free

time to eat breakfast but the group dont want to waste their time without doing anything, so they

decided to do the excel for the computation and the

table for the data sheet.

It is written in the procedure that the group are the

one who will make the set up but as the laboratory

assistant gave the tube it is already fix and ready

to use because if they are the one that will put the

lycopodium powder it will be messy and it is also

for our convinience.

A B C D

A. Kundts Tube with lycopodium powder Apparatus

B. Meter Stick

C. Thermometer

D. Cloth

As needed the powder inside the tube was

absolutely dry and distributed properly and equally.

The group also measure the length of the rod used

in the experiment as well as the room temperature

using the thermometer provided. And they also

make sure that the disk inside the tube and placed

at the center so that it could not affect the waves.

As the professor discuss the procedures, some of

the members try to grip the rod and do some

strokes to it but unfortunately they did not made a

good and perfect waves since they did not pull the

cloth completely off the rod and they did not apply

the proper technique that is acquired.

Figure 1. Set up for Experiment 303 Kundts Tube: Velocity of sound in solid

Figure 2.Front view of Kundts Tube showing the lycopodium powder inside it

After gathering data, just like the youngs modulus and the density of the rod, the group started to grip

the rod and made some strokes in back direction

only and not back and forth to have a consistent

result of waves in the tube.

After making some high pitch of sound using the

rod and rosin on it, successive powder hips are

present in the tube and the group measured it by

averaging those powder segments.

And After gathering the data needed, the group

computed the velocity of sound with 2 different

equation and compare the answers.

DATA AND RESULTS:

KUNDTS TUBE: VELOCITY OF SOUND IN SOLID

length of metal rod Lr 91.50 cm

average length powder

segments La

9.20 cm

temperature of air t 28 C

velocity of sound in air

va

348.8 m/s

velocity of sound in the

rod vr (from Equation 3)

3469.04 m/s

velocity of sound in the

rod vr

(from textbook)

3475 m/s

percentage error 0.17 %

density of the rod 8520 m/s

velocity of sound in the

rod vr

(From Equation 4)

3268.14 m/s

percentage error 5.95 %

Figure 3 Some is observing the equal distribution of

the powder, and some are measuring the length of the

rod, and recording the data gathered.

Figure 4 Showing the gripping of the rod to make

high pitch of sound and waves on the tube. Table 1. KUNDT'S TUBE: VELOCITY OF SOUND IN

SOLID

Figure 5 Measuring the length of the powder

segments

We got higher percentage error if we would

compare it with other group may be because we

used different velocity of sound in the rod from the

internet because there are many kinds of rod and

we got the velocity which is farther than the value

we have get. And may be some of the inconsistency

of our result is because of the average length of the

powder segments.

SAMPLE COMPUTATION

This shows how we get our data with the formula

given to us provided in the laboratory manual.

Heres the solution of our best result gathered.

Length of Metal Rod, Lr = 91.50 cm.

Average Length Powder Segments, La = 9.20 cm.

Temperature of air, t = 28 C

Velocity of sound in the rod, Vr = 3475 m/s Youngs Modulus of the rod, Y = 9.101010 Pa Density of the rod, = 8520 kg/m3

Determining the velocity of sound in air, Va :

= 332 + 0.6 ()

= 332 + 0.6 (28)

= 348.8 /

Determining the velocity of sound in the rod, Vr : (from Equation 3)

= (

) ()

= (91.50

9.20) (348.8)

= 3469.04 /

Percentage Error

% =| 1|

1 100%

% = |3475 3469.04 |

3475 100 %

% = 0.17%

Determining the velocity of sound in the rod, Vr : (from Equation 4)

=

= 9.11010

8520

= 3268.14 /

Percentage Error:

% = | 2|

2 100 %

% = |3469.04 3268.14|

3268.14 100 %

% = 6.14%

DISCUSSION

In this experiment, Kundts Tube: Velocity of Sound in Solid, we only consume shorter time in performing the experiment compared to the past

experiments weve already done. It is expected that we can get small percentage error since it is not

about temperature. As the cloth with rosin was grip

and has been rubbed on the rod, it produces high

pitch and longitudinal waves were produced in a

metal rod and on air column. And in minimizing the

percentage error of our experiment as we measure

the length of the powder segments, we get its

average. And because this experiment was very

simple we used to try several trials to see if we are

getting the correct average length of the powder

segments.

As we get the data we want to see, we use the

equation 3 on the laboratory manual:

= (

) ()

to get the velocity of sound in the rod equal to

3469.04 m/s and comparing it to the velocity of

sound in the rod from the internet we attain the

0.17 percentage error. And after that we also get

the velocity of sound in the rod using the equation

4 in the laboratory manual:

=

And it gives us the result 3268.14 m/s and we

compare it to the velocity of sound using equation

3 and we get the 6.14 percentage error. We got

higher percentage error if we will compare the both

velocity it is maybe because the first factor that

made it wrong is the density weve used in the experiment since there are many kinds of rod we

got different density compared to the other group,

and as what Ive written earlier is the average length of the segments.

I just observed that it would be better if the data

needed in the experiment will be indicated on the

laboratory manual because in our case we get

different kinds of rods and this made our data

inaccurate and different from others, even if we

have internet there are many different data that we

can use which gave us a hard time to compute

small percentage error. And as we brought back the

laboratory apparatus to the laboratory assistant

they told us that we should not rotate the tube, so

I just concluded that if we did not rotate the tube it

will be harder for us to measure the segments

because it is not clear anymore to see the length.

CONCLUSION

Our objectives in this experiment were achieve by

our group which were, to determine the velocity of

the sound in a metal rod and, to determine the

speed of sound in the tube applying the principles

of resonance.

The theory is that the sound in solid can be

determined by applying the principle of resonance.

In this experiment, when the metal rod was

vibrated, it produced longitudinal waves similar to

resonating air column in a tube open at both ends.

By using the principle of resonance, we were able

to compute the speed of sound in a metal rod by

equating the frequencies of the metal rod and air.

The computed speed of sound in metal rod was

3469.04 m/s, which is relatively close to the value

of the 3268.14 m/s from the equation 4.

We attain everything on the objectives by trying

several attempts on the rod and gathered many

data as we can with the given time given to us. By

the stroke applied to the rod, it produces friction as

well as longitudinal waves on the tube from the rod

at equal frequency that result with having a high

pitch sound. The velocity of sound was known

because of the visible wave pattern made of

lycopodium powder.

The changes in velocity of sound in solid in the

experiment with the changes in the position of the

nodes, as it divided the rod into a certain segment

I can say that the division is inversely proportional

on the changes of the velocity. And based from the

definition that the velocity of sound in an air column

can be described as either closed or open type. Its

difference is that the wave produced, to be specific,

it is about the nodes and the antinodes. Since we

used the closed type on our experiment antinode is

the open end and node is the close end. And with

this experiment we also consider the density and

youngs modulus of the rod, wherein the velocity is directly proportional to the youngs modulus while inversely proportional to the density of the rod.

ACKNOWLEDGEMENT

I would like to express my special thanks to my

group mates who help each other to made this

laboratory report, on gathering data from the

experiment and not wasting their time on doing non

sense things while waiting for the laboratory

apparatus. And I would also like to thank the

student assistants who guide me and suggest some

corrections on my previous laboratory where I can

make a better laboratory report. Lastly, my high

school friends who cheer me up and encourage me

to give enough time in doing this report.

REFERENCES

[1] Young, H. D., Freedman, R. A., & Ford, L.,

UNIVERSITY PHYSICS with Modern Physics,

twelfth, 2008

PHYSICS TRIVIA

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of Light Amplification by Stimulated Emission of Radiation.

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cm taller SOURCE: http://4bernoulli.blogspot.com