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The following physics responses are provided by a student and, as such, should be considered in that context. While every effort is made for accuracy, absolute correctness cannot be fully guaranteed.
| C | I | Question | Answer |
|---|---|---|---|
| 14 | Consider a vibrating string that makes a sound wave that moves through the air. As the guitar string moves up and down, the air molecules that are a certain horizontal distance from the string will move: 1) up and down. 2) toward and away from the guitar string. 3) back and forth along the direction of the length of the string. 4) in circles around the guitar string. 5) none of the above. | toward and away from the guitar string. | |
| 14 | Doubling the tension in a guitar string will change its natural frequency by what factor? | 1.4 | |
| 14 | For a standing wave in an air column in a pipe that is open at both ends, there must be at least: 1) one node and one antinode. 2) two nodes and one antinode. 3) two antinodes and one node. 4) two nodes and two antinodes. 5) none of the above. | two antinodes and one node. | |
| 14 | For a standing wave on a string the wavelength must equal: 1) the distance between adjacent nodes. 2) the distance between adjacent antinodes. 3) twice the distance between adjacent nodes. 4) the distance between supports. 5) both choices C and D are valid. | twice the distance between adjacent nodes. | |
| 14 | How far away is a lightning strike if you hear the thunderclap 3.00 s after you see the lightning bolt strike? (vsound = 340 m/s, vlight = 3*10^8 m/s) | 1 020 m | |
| 14 | I stretch a rubber band and "plunk" it to make it vibrate in its fundamental frequency. I then stretch it to twice its length and make it vibrate in the fundamental frequency once again. The rubber band is made so that doubling its length doubles the tension and reduces the mass per unit length by a factor of 2. The new frequency will be related to the old by a factor of: | 1.0 | |
| 14 | If a guitar string has a fundamental frequency of 500 Hz, what is the frequency of its second overtone? | 1 500 Hz | |
| 14 | If I triple the mass per unit length of guitar string, its natural frequency changes by what factor? | 0.58 | |
| 14 | If I0 = 10^-12 W/m2 is the threshold of hearing, a sound with intensity I1 = 10^-11 W/m2 will give a certain decibel level. Suppose a new sound has an intensity I2 = I1^2/I0. What is the new decibel level? | 20 | |
| 14 | If one-third of the members of a symphony orchestra are absent because of head colds, thus reducing the overall intensity of sound by 33%, what will be the reduction in the decibel level? | 1.7 dB | |
| 14 | If the distance between a point sound source and a dB detector is increased by a factor of 4, what will be the reduction in intensity level? | 12 dB | |
| 14 | If the intensity of a sound is increased by a factor of 100, how is the decibel level changed? The new decibel level will be: 1) two units greater. 2) double the old one. 3) ten times greater. 4) twenty units greater. 5) ten units greater. | twenty units greater. | |
| 14 | If the tension on a guitar string is increased by a factor of 3, the fundamental frequency at which it vibrates is changed by what factor? | sqrt(3) | |
| 14 | If two adjacent frequencies of an organ pipe closed at one end are 550 Hz and 650 Hz, what is the length of the organ pipe? (vsound = 340 m/s) | 1.70 m | |
| 14 | In the afternoon, the decibel level of a busy freeway is 80 dB with 100 cars passing a given point every minute. Late at night, the traffic flow is only 5 cars per minute. What is the late-night decibel level? | 68 dB |