AP Physics 1 : Sound Waves
年代tudy concepts, example questions & explanations for AP Physics 1
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Example Questions
Example Question #1161 :Ap Physics 1
Consider a 37cm long harp string with a fundamental frequency of 440Hz.
年代uppose the string is pressed down in such a way that only a 10cm length of string vibrates. What is the speed of the wave produced when the string is plucked in terms of
The speed of a wave is a property of the medium, it is not affected by the length of the string. The frequency may change, but the speed remains constant. There is no change in the speed.
Example Question #1162 :Ap Physics 1
Consider a 37cm long harp string with a fundamental frequency of 440Hz.
If only half of the string is allowed to vibrate, what frequency will be heard?
年代ince the speed of the wave does not change based on the length of the string and we know it has a fundamental frequency of 440Hz, a string of half the length will vibrate at twice the frequency, 880Hz. This makes sense as it will sound higher in pitch. You can try this with a rubber band on a shoebox. Plucking it while placing your finger halfway along the band will result in a higher pitched sound.
Example Question #1163 :Ap Physics 1
Consider a 37cm long harp string with a fundamental frequency of 440Hz.
What is the wavelength of the second harmonic of the string?
The wavelength of the second harmonic of a standing wave on a string is just the length of the string. For the second harmonic, an entire cycle occurs on the length of the string. Therefore, the wavelength of the second harmonic for this string is 37cm or 0.37m. The wavelength for the first harmonic, or fundamental, is twice the length of the string, as this is when one half a cycle occurs over the length of the string.
Example Question #1164 :Ap Physics 1
If the first harmonic of a string has frequency
谐波描述wavele之间的关系ngths and frequency on a string. A given string will have a wave speed associated with it. Given this wave speed, the harmonics are the frequencies at which half-wavelengths occur along the length of the string. For instance, the first harmonic is the frequency at which a half-wavelength occurs over the string. The second harmonic completes one wave over the string. The string is 1.5 times the wavelength of the third harmonic and so on. Therefore, the
Example Question #1165 :Ap Physics 1
鉴于20 kj的能量冲击盘的窗口e over a period of 5s with dimensions 2.5m by 4m, what is the sound level in decibels?
The formula for intensity,
Where
The power
年代olve for intensity.
The formula for sound level
Example Question #1166 :Ap Physics 1
At a distance of
First we need to solve for intensity
In our case,
To solve for sound level
In this problem,
Example Question #1167 :Ap Physics 1
By what factor will the sound level in decibels change if the intensity is increased by a factor of
声音勒vel will change by a factor of
声音勒vel will change by a factor of
声音勒vel will change by a factor of
声音勒vel will change by a factor of
声音勒vel will change by a factor of
Recall that the formula for sound level
声音勒vel is proportional to intensity by:
If the intensity is increased by a factor of
Example Question #11 :年代ound Waves
A guitar player hits a wrong note. The note he's supposed to hit is
In order to find the velocity needed, we use the Doppler equation:
Where
Because we need the note to be the final note to be lower in frequency than the original frequency, we need to run away from it.
Example Question #12 :年代ound Waves
The speed of sounds is the fastest in which of the following media?
The speed of sound is constant in all media.
Glass
Vacuum
Water
Air
Glass
The speed of sound is fastest in the least compressible media of the lowest density. Sound does not propagate in a vacuum. Air and water are compressible media, so sound does not travel as fast in these as it does in glass, an incompressible medium. In general, the speed of sound is greatest in solids, and within each phase, faster as density decreases.
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