I believe it is the first one.
This is because of the Doppler Effect.
The Doppler Effect is when the frequency of the wave changes for an observer moving relative to the wave source.
Basically, as the police car moves away from you, the distance between you and the car increases, which makes the sound waves spread out.
In order to find out how long/wide/heavy/high/dense/deep/ massive/voluminous/reflective/opaque/ tansparent/warm/cold/hard/soft/ malleable/flexible/rigid/radioactive/old/ valuable/symmetrical/flat/regular/ irregular they are.
In a way that you can easily and conveniently describe to other people.
No answer is possible until we know the number that belongs after the words "... angular speed of ".
Answer:
8.60 g/cm³
Explanation:
In the lattice structure of iron, there are two atoms per unit cell. So:
where 
an and A is the atomic mass of iron.
Therefore:
This implies that:
= 
Assuming that there is no phase change gives:
= 8.60 g/m³
