The gravitational force between two objects is given by

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the separation between the two objects
In this problem,

,

and

, therefore the gravitational force between the two objects is
Answer:
f'=5.58kHz
Explanation:
This is an example of the Doppler effect, the formula is:

Where f is the actual frequency,
is the observed frequency,
is the velocity of the sound waves,
the velocity of the observer (which is negative if the observer is moving away from the source) and
the velocity of the source (which is negative if is moving towards the observer). For this problem:


I think it’s a because it the only reasonable answer
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