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

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 ms^-1 at an angle of ${60}^0$ with the source-observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 ms^-1), is: 
              

1. 100 Hz

2. 103 Hz

3. 106 Hz

4. 97 Hz

A speeding motorcyclist sees a traffic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving ahead of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speed of sound is 343 m/s, the frequency of the honk as heard by him will be:

1. 1332 Hz

2. 1372 Hz

3. 1412 Hz

4. 1454 Hz

The driver of a car travelling at a speed of 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s, the frequency of reflected sound as heard by the driver is:

1. 550 Hz

2. 555.5 Hz

3. 720 Hz

4. 500 Hz

An observer moving at a velocity of 20 m/s is moving away from a source moving at a speed of 10 m/s towards the observer.
If the frequency of the source is 'f', then find the frequency observed by the observer is: ( $v_{sound} = 330 m/s$ )

1. $\frac{32}{31}f$

2. $\frac{47}{23}f$

3. $\frac{31}{32}f$

4. 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

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 train moves towards a stationary observer at a speed of 34 m/s. The train sounds a whistle and its frequency registered is $f_1$. If the train's speed is reduced to 17 m/s, the frequency registered is $f_2$. If the speed of sound is 340 m/s , then the ratio $\frac{f_1}{f_2}$ is

1. $\frac{18}{19}$

2. $\frac{1}{2}$

3. 2

4. $\frac{19}{18}$

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