Question

A source emits sound with a frequency of 1000hz. It is moving at 20m/s the ratio of apparent frequency

Answer 1

Answer:

9:8

Solution :

When source is approaching the observer, the frequency heard <br>

n

a

=

(

v

v

−

v

S

)

×

n

=

(

340

340

−

20

)

×

1000

=

1063

H

z

<br> When source is receding the frequency heard <br>

n

r

=

(

v

v

+

v

S

)

×

n

=

340

340

−

20

×

1000

=

944

<br>

⇒

n

a

:

n

r

=

9 :8

<br> Short tricks :

n

a

n

r

=

v

+

v

S

v

−

v

S

=

340

+

20

340

−

20

=

9

8

<br> (speed of sound

v

=

340

m

/

s

Explanation:

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