A observer is standing 10 m from a road on which a vehicle is approaching him at a speed of 96 /hr when the vehicle is 50 m away from him, it blows a horn of frequency 8000 Hz what will be the frequency observed by the observer?
= 8668 Hz
The correct answer is: 8668
Consider a pipe 12 cm in length. Find by how much percentage does the fundamental frequency change when the pipe which was originally open at both ends is now closed from one side.
Exactly half wavelength fits the pipe,
When one end is closed then of a wavelength fits the pipe
The correct answer is: 50
In extremely, cold places, the temperatures are slow that it effects the speed of sound in air. On a day with temperature -35°C, a source emits sound at a frequency of 1050 Hz & moves away from an observer at 25 m/s, the frequency that the observer measures is 97141 Hz. Find the speed of sound (in m/s).
The correct answer is: 309
An organ pipe, closed at one and open at the other, is designed to have a fundamental frequency of c( 131 Hz) what is the frequency of the next higher harmonic for this pipe?
For a pipe of length L, Closed at one and open at the other end, the resonant frequencies are given by
where n - 1, 3, 5
and v is the speed of the sound
Thus, a fundamental frequency is and the next harmonic has a frequency For the next harmonic,
f(n = 3) = 3f(n = 1) = 3 x 131
= 393 Hz
The correct answer is: 393
At 20°C, a pipe open at both ends resonates at a frequency of 440 Hz. At what frequency does the same pipe resonate on a cold day when the speed of sounds is 3 percent lower than it would be at 20°C
Since, 2L remains constant
The correct answer is: 433.3
The equation of a wave traveling on a string is . If x and y are in cm, then velocity of wave is ________ (in cm/s).
The correct answer is: 64
A distant galaxy is observed to have its hydrogen-β line shifted to a wavelength of 580 nm find the approximate velocity of recession of the distant galaxy in unit of 108 m/s
Applying the relativistic doppler effect
The correct answer is: 0.84
Sound wave moving at 350 m/s difference out of a speaker enclosure with an opening that is a long rectangular slit 0.14m across. At about what frequency will the sound first disappear at an angle of 45° from the normal to the speaker face?
The first minimum is determined by
The correct answer is: 3500
A source is emitting sound with frequency 4371 Hz. Find the magnitude of difference of the two velocities with which the observer must move to observe a frequency that is 20% higher and 20% lower than the actual frequency (in m/s).
fs = frequency of source = 4371 Hz
When ovserved frequency is 20% higher
= 68 m/s
When the observed frequency is 20% lower
(-) sign indicates that the observer is moving away from the source?
∴ Difference of velocities = 68 - (-68)
= 136 m/s
The correct answer is: 136
During a Hurricane, a 1200 Hz warning siren in the town hall sounds the wind is blowing at 55 m/s in a direction from the siren towards a person 1 km away. With what frequency does the sound wave reach the person. The speed of sound in air in 330 m/s.
C - speed of sound in medium
V0, V5 - Speeds of the observer & source relative to the medium
Since both the source & Since both the source & observer move at the speed of the wind
∴ These is no relative motion between them
No doppler effect
∴ f0 = 1200 Hz
The correct answer is: 1200