Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • Please help! A man is watching two trains, one leaving and one is coming with equal speed of 4 m/s. If they sound horns, each of frequency 240 Hz, the number of beats heard by man is (Given velocity of sound in air = 320 m/s)

A man is watching two trains, one leaving and one is coming with equal speed of 4 m/s. If they sound horns, each of frequency 240 Hz, the number of beats heard by man is (Given velocity of sound in air = 320 m/s)

  • Option 1)

    6

  • Option 2)

    3

  • Option 3)

    0

  • Option 4)

    12

 

Answers (1)

best_answer

Apparent frequency due to train which is coming v_{1}' = \frac{c}{c-v_{s}}v_{o}

Apparent frequency due to leaving train  v_{2}' = \frac{c}{c+v_{s}}v_{o}

no. of beats v_{1}' - v_{2}' = \left [ \frac{1}{316} - \frac{1}{324} \right ] 320 X 240

So v_{1}' - v_{2}' = 6

 

Frequency of sound when observer is stationary and source is moving towards observer -

\nu {}'= \nu _{0}.\frac{C}{C-V_{s}}
 

- wherein

C= speed of sound

V_{s}= speed of source

\nu _{0}= original frequency

\nu {}'= apparent frequency

 

 

 

 


Option 1)

6

This is correct.

Option 2)

3

This is incorrect.

Option 3)

0

This is incorrect.

Option 4)

12

This is incorrect.

Posted by

Aadil

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE

Similar Questions

Trending Articles/News

anam-khan

BTech aspirant from north-east or UT? Apply for CSAB NEUT counselling 2025 today
anam-khan

JoSAA round 2 cut-off 2025 out; BTech closing ranks for top engineering courses at IITs
anam-khan

Goa Engineering Admission 2025: 1,415 eligible for BE seats; merit list on June 27

Latest Question