A source and listener are both moving towards each other at a speed of v/10, where v is the speed of sound. If the frequency of the note emitted by the source is f, the frequency heard by the listener would be nearly :
1. 1.11 f
2. 1.22 f
3. f
4. 1.27 f

A motor car blowing a horn of frequency 124vib/sec moves with a velocity 72 km/hr towards a tall wall. The frequency of the reflected sound heard by the driver will be (velocity of sound in air is 330 m/s) 

(1) 109 vib/sec

(2) 132 vib/sec

(3) 140 vib/sec

(4) 248 vib/sec

A source of sound of frequency n is moving towards a stationary observer with a speed S. If the speed of sound in air is V and the frequency heard by the observer is n₁, the value of n₁/n is 

(1) (V + S)/V

(2) V/(V + S)

(3) (V – S)/V

(4) V/(V – S)

An observer is moving away from the source of the sound of frequency 100 Hz. His speed is 33 m/s. If the speed of sound is 330 m/s, then the observed frequency is :

(1) 90 Hz

(2) 100 Hz

(3) 91 Hz

(4) 110 Hz

An observer standing at the station observes frequency 219 Hz when a train approaches and 184 Hz when train goes away from him. If velocity of sound in air is 340 m/s, then velocity of train and actual frequency of whistle will be 

(1) $15.5m{s}^{-1},200Hz$

(2) $19.5m{s}^{-1},205Hz$

(3) $29.5m{s}^{-1},200Hz$

(4) $32.5m{s}^{-1},205Hz$

A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec)
1. Zero
2. 2
3. 8
4. 4

The driver of a car traveling with speed 30 meters per second towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 meters per second, the frequency of the reflected sound as heard by the driver is :

1. 720 Hz

2. 555.5 Hz

3. 550 Hz

4. 500 Hz

A source of sound is travelling with a velocity 40 km/hour towards the observer and emits the sound of frequency 2000 Hz. If the velocity of sound is 1220 km/hour, then what is the apparent frequency heard by an observer 

1. 2210 Hz

2. 1920 Hz

3. 2068 Hz

4. 2086 Hz

A source of sound and listener are approaching each other with a speed of 40 m/s. The apparent frequency of note produced by the source is 400 cps. Then, its true frequency (in cps) is (velocity of sound in air = 360 m/s) 

1. 420

2. 360

3. 400

4. 320

A siren emitting sound of frequency 500 Hz is going away from a static listener with a speed of 50 m/sec. The frequency of sound to be heard, directly from the siren, is :

(1) 434.2 Hz

(2) 589.3 Hz

(3) 481.2 Hz

(4) 286.5 Hz