Question

Jack is playing a

solo on the harpsichord, and John on a

bottle jug is trying to produce a beat frequency by playing an identical note but running

towards Jack. Jack is playing a standard concert note at

440.0 Hz, and wants to create a beat frequency of 15 Hz. How fast

Must John be moving if he is playing the same note as Jack? The temperature

outside is 5.00 o C.

Answer 1

Here we have given,

fo= 440 Hz

Beat frequency Delta(f) = 15 Hz

Now as we have the relation as,

f'/fo= (v/v-vo)

Here v is the speed of sound and will be 334.32 m/s at 5 ° C

And vo is the speed of jhon.

f' = fo(334.32/334.32-vo)

And subtracting both side by fo we will get,

f'-fo = fo(334.32/334.32 -vo) - fo

We we have given beat frequency f'-fo = 15 Hz

So that,

15 = fo(334.32/334.32-vo) - fo

On solving this we will get,

334.32 -vo = 323.2984

So that, vo = 11.0215 m/ s

Hence John is moving with 11.0215 m/s .