Question

An engine blowing a whistle of frequency 288Hz moves with speed 15m/s. Find the apparent frequency of whistle heard by an observer at rest to which the engine is approaching. The velocity of sound in air is 330 m/s.

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Solution

The apparent frequency of wave received by stationary observer when source moves towards the observer is given by,

straight v apostrophe equals fraction numerator straight V over denominator straight V minus straight u end fraction straight v

We have,

Velocity space of space sound space in space air comma space space straight V equals 330 straight m divided by straight s Speed space of space engine comma space straight u equals 15 straight m divided by straight s

Frequency of the engine,

straight v equals 288 HZ

Apparent frequency of whistle heard by an observer is,

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Mechanical Properties Of Fluids

An engine blowing a whistle of frequency 288Hz moves with speed 15m/s. Find the apparent frequency of whistle heard by an observer at rest to which the engine is approaching. The velocity of sound in air is 330 m/s.

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