A source of sound moves away with the velocity of sound from a stationary observer. The frequency of the sound heard by the observer:

1. remains the same

2. is doubled

3. is halved

4. becomes infinity
 

Two cars moving in opposite directions approach each other with speed of 22m/s and 16.5 m/s respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340m/s]

1. 350Hz

2. 361Hz

3. 411Hz

4. 448Hz

A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of $15{\mathrm{ms}}^{-1}$. The frequency of sound that the observer hears in the echo reflected from the cliff will be:
(Take, velocity of sound in air=$330$ ${\mathrm{ms}}^{-1}$)
1. 800 Hz
2. 838 Hz
3. 885 HZ
4. 765 Hz

A speed motorcyclist sees a traffic jam ahead of him. He slows down to 36km/h. He finds that traffic has eased and a car moving in front of him at 18km/h is honking at a frequency of 1392Hz. If the speed of sound is 343m/s, the frequency of the honk as heard by him will be 
1. 1332Hz
2. 1372Hz
3. 1412Hz
4. 1454Hz 

A train moving at a speed of 220 ${\mathrm{ms}}^{-1}$ towards a stationary object, emits a sound of frequency 1000 Hz. Some of the sound reaching the object gets reflected back to the train as an echo. The frequency of the echo as detected by the driver of the train is
(speed of sound in air is 330 ${\mathrm{ms}}^{-1}$)
1. 3500Hz
2. 4000Hz
3. 5000Hz
4. 3000Hz

The driver of a car traveling at a speed of 30 m/s towards a hill sounds a horn at a frequency of 600 Hz. If the velocity of sound in air is $330 m{s}^{-1},$ the frequency of reflected sound as heard by the driver is 
1. 550 Hz                             
2. 555.5 Hz
3. 720 Hz                             
4. 500 Hz
 

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 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

Two cars moving in opposite directions approach each other at speeds of 22 m/s and 16.5 m/s, respectively. The driver of the first car blows a horn with a frequency of 400 Hz. The frequency heard by the driver of the second car is [assume velocity of sound to be 340 m/s]:

1. 361 Hz

2. 411 Hz

3. 448 Hz

4. 350 Hz
 

A siren emitting a sound of frequency \(800\) Hz moves away from an observer towards a cliff at a speed of \(15\) ms^-1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is:
(Take, the velocity of sound in air = \(330\) ms^-1)
1. \(800\) Hz
2. \(838\) Hz
3. \(885\) Hz
4. \(765\) Hz