A small source of sound moves on a circle as shown in figure (16-Q1) and an observer is sitting at O. Let v₁, v₂, v₃ be the frequencies heard when the source is at A, B and C respectively.



A. v₁ > v₂ > v₃

B. v₁ = v₂ > v₃

C. v₂ > v₃ > v₁

D. v₁ > v₃ > v₂

A train, standing at the outer signal of a railway station blows a whistle of frequency 400 Hz in still air. (i) What is the frequency of the whistle for a platform observer when the train (a) approaches the platform with a speed of 10 m s^–1, (b) recedes from the platform with a speed of 10 m s^–1? (ii) What is the speed of sound in each case? The speed of sound in still air can be taken as 340 m s^–1.

A source emitting a sound of frequency v is placed at a large distance from an observer. The source stats moving towards the observer with a uniform acceleration a. Find the frequency heard by the observer corresponding to the wave emitted just after the source starts. The speed of sound in the medium is u.

A person riding a car moving at 72 km/h sounds a whistle emitting n wave of frequency 1250 Hz, What frequency will be heard by another person standing on the road (a) in front of the car (b) behind the car? Speed of sound in air = 340 m/s.

Find the fundamental, first overtone and second overtone frequencies of an open organ pipe of length 20 cm. Speed of sound in air is 340 m s^-1.

A source of sound S and a detector D are placed at some distance from one another. A big cardboard is placed near the detector and perpendicular to the line SD as shown in figure (16-E1). It is gradually moved away and it is found that the intensity changes from a maximum to a minimum as the board is moved through a distance of 20 cm. Find the frequency of the sound emitted. Velocity of sound in air is 336 m/s.

Two audio speakers are kept some distance apart and are driven by the same amplifier system. A person is sitting at a place 6.0 m from one of the speakers and 64 in from the other. If the sound signal is continuously varied from 500 Hz to 5000 Hz, what are the frequencies for which there is a destructive interference at the place of the listener? Speed of sound in air = 320 m/s.

A sound source, fixed at the origin, is continuously emitting sound at a frequency of 660 Hz. The sound travels in air at a speed of 330 m s^-1. A listener is moving along the line x=336 m at a constant speed of 26 m s^-1. Find the frequency of the sound as observed by the listener when he is (a) at y = — 140 m, (b) at y = 0 and (c) at y = 140 m.

A violin player riding on a slow train plays a 440 Hz note. Another violin player standing near the track plays the same flute, When the two are close by and the train approaches the person on the ground, he hears 4.0 beats per second. The speed of sound in air = 340 m/s. (a; Calculate the speed of the train. (b) What beat frequency is heard by the player in the train?

An open organ pipe has a length of 5 cm. (a) Find the fundamental frequency of vibration of this pipe. (b) What is the highest harmonic of such a tube that is in the audible range? Speed of sound in air is 340 m s^-1 and the audible range is 20-20,000 Hz.

In Quincke’s experiment the sound detected is changed from a maximum to a minimum when the sliding tube is moved through a distance of 2.50 cm. Find the frequency of sound if the speed of sound in air is 340 m s^-1.