My answer is incorrect also process is wrong, please write your explanation(process detail) why the correct answer is an "observer" and write about why my answer is wrong.

Considerasituationwhereasource isemittingapainfullyhigh-frequencysoundandyouwanttoreducetheobservedfrequency ofthesoundbya proportionp,where0???1.

a. Which is more effective for reducing the frequency of the observed sound: having the observer move or havingthesource move?(Be suretoproveyouranswer mathematically.)

My process:

To check the effectiveness of reducing sound. We reduce the velocity of both by some factorsay1/3times, that gives,

For observer move,

vo=v/3

then,

v/3=v(1-po)

1/3=1-po

po=2/3

Similarly, for source move,

vs=v/3

then,

vs=(-1+1/ps)v

v/3=(-1+1/ps)v

1/3=(-1+1/ps)

1/ps=4/3

ps=3/4

Clearly,

ps>po when the velocity of both is reduced. So the movement of the source is reduced more frequency than observer movement.

Hence, the source move is more effective to reduce frequency.

Professor's Answer and process

the source mover (Be sure to prove your answer mathematically.) A couple different methods to solve this. Method 1, Parta: Choose a specific value of P and solve for the required No and NS : I'll choose P = 2: 1/2 N = 1/ 2 No = and Ns = 1 - 2 N = N : NS NI - N 1/2 So The observen needs to move at for whereas the source needs to move at the fall as to reduce the frequency by 3. BUT this isn't enough- how do I know whether the observer moving is more effective fall all p an eu .be the source moving is more effective for somewhether - maybe The source moving is more effective for some method 1 otherp . If they switch then there must be some I part b: for which as = No. 1 - P 2 P ( 1-p) = P = > p - P = P = - p = 0 = 1 =0 PIO is the only reduction proportion for which moving the source is as effective as moving the byserver So never for any reduction. is more effectiveP=0 is the only reduction moving the source is as effective as moving The angeroll so never for any reduction . moving the observer is more effective