LAB 11

PhysicsLab11 June 23, 2010 Name __________________
Dr Dave Menke, Instructor

I. Title: String Phone – Waves in a String

II. Purpose: to observe and hear the effects of waves on a string and to make an old fashioned “tin can” phone

III. Equipment: 2 cans each team, string – about 10 meters +/-; awl or ice pick

IV. Procedure:
1. Measure out about 10 meters of string
2. punch a small hole in the end of one can
3. carefully thread string through the hole and tie a knot
4. pull the string until it reaches the hole
5. If the knot slips through the hole, make a larger knot so that it won’t slip through.
6. If you hadn’t guessed, the knot needs to be on the inside of the can.
7. Repeat with the second can
8. You and your partner need to go to a quieter place to “talk” to each other; extraneous noise will negate the results.
9. In your “quiet place” pull the cans as far apart as possible, without making the knot pop out of either can. If that happens, oops! Start over!
10. Have one partner think of a simple sentence and write it down, but don’t show the other partner.
11. Have that one partner say that simple sentence into his/her can, in a regular voice
12. The other partner needs to cup his/her ear with the can and listen, as if listening to a sea shell for the sound of the ocean.
13. The other partner needs to listen, and remember the simple sentence, then write it down.
14. Repeat this with the second partner writing his/her own sentence, then saying it into the can, and having the other partner listen, write down what she or he hears.
15. Clean up, put away toys, etc.
16. Return to your seats. Share what you heard with what your partner really said and vice versa
17. Determine how successful you were

V. Data, observations, calculations:
1. Sentence you wrote down and said: “_______________________.”

2. Sentence that your partner heard you say: “__________________.”

3. Difference, if any:

4. Sentence you heard: “__________________________.”

5. Sentence your partner wrote down and said: “__________________.”

6. Difference, if any:

VI. Results: How successful?

__This experiment was very successful as we were able to hear each other very clearly and with a high level of accuracy.

__This experiment was an abysmal failure as we were NOT able to hear each other very clearly at all.

__We were also able to approximate the speed of the sound wave in the string.

__We were also unable to approximate the speed of the sound wave in the string.

VII. Error:

A. Quantitative: Explain the reason for any differences in V 3. and V. 6.



B. Qualitative:
1. Personal –
2. Systematic –
3. Random –

VIII. Questions:
1. What causes the sound to travel along the string?

2. How fast does the sound travel on the string?

3. How can one find out how fast the sound traveled along the string?

4. What is a sonic boom? Explain in detail.