A source of sonic oscillations with frequency `n=1700Hz` and a receiver are located on the same normal to a wall. Both the source and receiver are stationary, and the wall recedes from the source with velocity `u=6.0(m)/(s)`. Find the beat frequency registered by the receiver. The velocity of sound is `v=340(m)/(s)`.

Answer

59

Explanation

frequency pf direct sound recived by observer `= f`
frequency of sound reflected by wall
`f' = f_(0)"(v)/(v + u)`
frequency of this sound as received by observer `=f`
`f'' = f'(v - u)/(v) = f_(0)((v - u)/(v + u)) = ((340 - 6)/(340 + 6)) = 1700 ((334)/(346))`
Beat frequency `= |f'' - f| = 1700 (1 -(334)/(346)) = ((1700)/(346)) xx 12 ~ 59 Hz`