Question

An observer is standing between two vehicles, each moving with a speed 4 ms–1. One vehicle is approaching him and the other going away from him. If each vehicle is blowing a horn of frequency 240 Hz and the speed of sound is 320 ms–1, the number of beats per second will be

Solution

Correct option is

6

 

The apparent frequencies of the two sounds are

                           

                                        

SIMILAR QUESTIONS

Q1

Two waves of wavelength 2 m and 2.02 m moving with the same speed superpose to produce 2 beats per second. The speed of each wave is

Q2

The potential energy of a particle executing simple harmonic motion at a distance x from the equilibrium position is proportional to

Q3

 

Two travelling waves

                      

and                

are superposed on a string. The distance between adjacent nodes is

Q4

If the amplitude of a sound wave is doubled and its frequency reduced to one-fourth, the intensity of sound at the same point will

Q5

At a certain instant a stationary transverse wave is found to have maximum kinetic energy. The appearance of the string at that instant is a

Q6

 

The displacement y of a particle executing simple harmonic motion is given by 

                                     

The expression may be considered to be a result of the superposition of how many simple harmonic motions?

Q7

A wave of frequency 100 Hz is sent along a string towards a fixed end. When this wave travels back after reflection, a node is formed at a distance of 10 cm from the fixed end of the string. The speed of the incident (or reflected) wave is

Q8

A particle starts simple harmonic motion from the mean position O as shown in the figure. Its amplitude is A and its time period is T. At a certain instant, its speed is half its maximum speed. At this instant, the displacement x is

                                                         

Q9

 

The wave equation is 

                       

Where tx and y are in second, metre and centimeter respectively. The speed of the wave is

Q10

A spring is extended by a length l, the according to Hooke’s law