Sound Waves Physics - Sound Waves

A tuning fork of frequency 512Hz is vibrated with a sonometer wire and 6 beats per second are heard. The beat frequency reduces if the tension in the string is slightly increased. The original frequency of vibration of the string is:

1. 506Hz
2. 512Hz
3. 518Hz
4. 524Hz.

Consider the following statements about sound passing through a gas.

1. The pressure of the gas at a point oscillates in time.
2. The position of a small layer of the gas oscillates in time.

1. Both A and B are correct.
2. A is correct but B is wrong.
3. B is correct but A is wrong.
4. Both A and B are wrong.

A small source of sound moves on a circle as shown-in figure and an observer is sitting at 0. Let v₁, v₂, v₃ be the frequencies heard when the source is at A, B and C respectively.

1. v₁ > v₂ > v₃

2. v₁ = v₂ > v₃

3. v₂ > v₃ > v₁

4. v₁ > v₂ > v₂.

The speed of sound in a medium depends on:

1. The elastic property but not on the inertia property.
2. The inertia property but not on the elastic property.
3. The elastic property as well as the inertia property.
4. Neither the elastic property nor the inertia property.

An organ pipe, open at both ends, contains

1. Longitudinal stationary waves.
2. Longitudinal travelling waves.
3. Transverse stationary waves.
4. Transverse travelling waves.

A Kundt's tube apparatus has a copper rod of length 1.0m clamped at 25cm from one of the ends. The tube contains air in which the speed of sound is 340m/s. The powder collects in heaps separated by a distance of 5.0cm. Find the speed of sound waves in copper.

If the intensity of sound is doubled, by how many decibels does the sound level increase?

A steel tube of length 1.00m is struck at one end. A Find the time gap between the two hearings. Use the person with his ear close to the other end hears the table in the text for speeds of sound in various sound of the blow twice, one travelling through the body substances. of the tube and the other through the air in the tube. Find the time gap between the two hearings. Use the table in the text for speeds of sound in various substances.

Find the minimum and maximum wavelengths of sound in water that is in the audible range (20-20000Hz) for an average human ear. Speed of sound in water = 1450m/s.

A bullet passes past a person at a speed of 220m/s. Find the fractional change in the frequency of the whistling sound heard by the person as the bullet crosses the person. Speed of sound in air = 330m/s.

Two point sources of sound are kept at a separation of 10cm. They vibrate in phase to produce waves of wavelength 5.0cm. What would be the phase difference between the two waves arriving at a point 20cm from one source-

1. On the line joining the sources.
2. On the perpendicular bisector of the line joining the sources?

Two sources of sound S₁ and S₂ vibrate at same frequency and are in phase figure. The intensity of sound detected at a point P as shown in the figure is I₀.

1. If 0 equals 45^°, what will be the intensity of sound detected at this point if one of the sources is switched off?
2. What will be the answer of the previous part if = 60^°?

A person standing on a road sends a sound signal to the driver of a car going away from him at a speed of 72km/h. The signal travelling at 330m/s in air and having a frequencyof 1600Hz gets reflected d from the body of the car and returns. Find the frequency of the reflected signal as heard by the person.

A bat emitting an ultrasonic wave of frequency 4.5 × 10⁴Hz flies at a speed of 6m/s between two parallel walls. Find the two frequencies heard by the bat and the beat frequency between the two. The speed of sound is 330m/s.

Two sources of sound, S₁ and S₂, emitting waves of equal wavelength 20.0cm, are placed with a separation of 20.0cm between them. A detector can be moved on a line parallel to S₁S₂, and at a distance of 20.0cm from it. Initially, the detector is equidistant from the two sources. Assuming that the waves emitted by the sources are in phase, find the minimum distance through which the detector should be shifted to detect a minimum of sound.

Two identical tuning forks vibrating at the same frequency 256Hz are kept fixed at some distance apart. A listener runs between the forks at a speed of 3.0m/s so that he approaches one tuning fork and recedes from the other figure. Find the beat frequency observed by the listener. Speed of sound in air = 332ms/s.

A car moves with a speed of 54km/h towards a cliff. The horn of the car emits sound of frequency 400Hz at a speed of 3.35m/s.

1. Find the wavelength of the sound emitted by the horn in front of the car.
2. Find the wavelength of the wave reflected from the cliff.
3. What frequency does a person sitting in the car hear for the reflected sound wave?
4. How many beats does he hear in 10 seconds between the sound coming directly from the horn and that coming after the reflection?

Two submarines are approaching each other in a calm sea. The first submarine travels at a speed of 36km/h and the other at 54km/h relative to the water. The first submarine sends a sound signal (sound waves in water are also called sonar) at a frequency of 2000Hz.

1. At what frequency is this signal received by the second submarine?
2. The signal is reflected from the second submarine. At what frequency is this signal received by the first submarine. Take the speed of the sound wave in water to be 1500m/s.

Two stereo speakers are separated by a distance of 2.40m. A person stands at a distance of 3.20m directly in front of one of the speakers as shown in figure, Find the frequencies in the audible range (20-2000Hz) for which the listener will hear a minimum sound intensity. Speed of sound in air = 320m/s.

The absolute temperature of air in a region linearly increases from T₁ to T₂ in a space of width d. Find the time taken by a sound wave to go through the region in terms of T₁, T₂, d and the speed v of sound at 273K. Evaluate this time for T₁ = 280K, T₂ = 310K, d = 33m and v = 330m/s.

At a prayer meeting, the disciples sing JAI-RAM JAI-RAM. The sound amplified by a loudspeaker comes back after reflection from a building at a distance of 80m from the meeting. What maximum time interval can be kept between one JAI-RAM and the next JAI-RAM so that the echo does not disturb a listener sitting in the meeting. Speed of sound in air is 320m/s.

Find the change in the volume of 1.0 litre kerosene when it is subjected to an extra pressure of 2.0 x 10⁵N/m² from the following data. Density of kerosene = 800kg/m³ and speed of sound in kerosene = 1330m/s.

A source of sound emitting a 1200Hz note travelg along a straight line at a speed of 170m/s. A detector is placed at a distance of 200m from the line of motion of the source.

1. Find the frequency of sound received by the detector at the instant when the source gets closest to it.
2. Find the distance between the source and the detector at the instant it detects the frequency 1200Hz. Velocity of sound in air = 340m/s.

A train running at 108km/h towards east whistles at a dominant frequency of 500Hz. Speed of sound in air is 340m/s.

1. What frequency will a passenger sitting near the open window hear?
2. What frequency will a person standing near the track hear whom the train has just passed?
3. A wind starts blowing towards east at a speed f 36km/h. Calculate the frequencies heard by the passenger in the train and by the person standing near the track.

A sound wave of frequency 100Hz is travelling in air. The speed of sound in air is 350m/s.

1. By how much is the phase changed at a given point in 2.5ms?
2. What is the phase difference at a given instant between two points separated by a distance of 10.0cm along the direction of propagation?