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One train is approaching an observer at rest and another train is receding from him with the same velocity `4 m//s` . Both trains blow whistles of same frequency of `243 H_(Z)` . The beat frequency in `H_(Z)` as heard by observer is (speed of sound in air = `320 m//s`)

A

`10`

B

`6`

C

`4`

D

`1`

Text Solution

Verified by Experts

The correct Answer is:
B
`V_(S_(1))=V_(S_(2))=4m//s`, `n=243Hz`, `Deltan~~(2nV_(S))/(V)`
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