Answer:
There is no change, unless your mass is somehow at the quantum level, at which the concept of half-life breaks down.
Half life is a property of the specific radioactive isotope...NOT of the initial sample's mass.
Frequency is defined as the number of repetitions of waves occurring in 1 second. The frequency heard by the man as the ambulance move toward him will be greater than 450 Hz.
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What is the frequency ?</h3>
Frequency is defined as the number of cycles completed in 1 second. Frequency is given by the formula as,

As the formula shows frequency is inversely proportional to the time that shows if the time is decreasing frequency will increase and vice versa.
In the above case, the ambulance is moving toward the men. So that the time to meet up is decreased that's why the frequency will be greater than the initial frequency from the siren.
Hence the frequency heard by the man as the ambulance move toward him will be greater than 450 Hz.
To learn more about frequency refer to the link ;
brainly.com/question/4393505
Simply subtract the two velocities and divide by 8.1,

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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey
Haploid and diploid cells