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JEE Main20236 Apr 2023Morning ShiftPhysicsWaves and SoundActual

A person driving car at a constant speed of 15 m s - 1 is approaching a vertical wall. The person notices a change of 40 Hz in the frequency of his car’s horn upon reflection from the wall. The frequency of horn is _______Hz . (Given: Speed of sound: 30 m s - 1 )

Correct answer

0

Step-by-step solution

The formula to calculate the frequency f ' as heard by an observer with respect to the frequency f produced from a source is given by f ' =   v ± v o v ∓ v s f       . . . . ( 1 ) where, v is the speed of sound in air, v o is the speed of the observer and v s is the speed of the source. In the first situation, the source is the moving car and the observer is the wall. Hence, the frequency f w as heard on the wall can be written as f w =   v - 0 v - v c f =   v v - v

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