An engine is moving towards a wall with a velocity 50 m s^-1 emits a note of 1.2 kHz. Speed of sound in air =350 m s^-1. The frequency of the note after reflection from the wall as heard by the drive…

Question

An engine is moving towards a wall with a velocity 50 m s^-1 emits a note of 1.2 kHz. Speed of sound in air =350 m s^-1. The frequency of the note after reflection from the wall as heard by the driver of the engine is

Accepted Answer

Correct answer: C. (c) The reflected sound appears to propagate in a direction opposite to that of direct sound of engine. Thus the source and the observer can be presumed to approach each other with same velocity. v^ '= v(v+v_0)(v-v_S)=v ( v+v_Sv-v_S )( ∵v_0=v_S) or v^ '=1.2 ( 350+50350-50 )= 1.2 400300=1.6 kHz

$An engine is moving towards a wall with a velocity 50 m s^{- 1} emits a note of 1.2 kHz . Speed of sound in air = 350 m s^{- 1} . The frequency of the note after reflection from the wall as heard by the driver of the engine is$

Solution

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