A variable is a letter so just be like
13a or something like that
For a stationary siren on a firehouse is blaring at 81Hz. Assume the speed of sound to be 343m/s, the frequency perceived is mathematically given as'
F=81.721Hz
<h3>What is the
frequency perceived by a
firefighter racing toward the station at 11km/h?</h3>
Generally, the equation for the doppler effect is mathematically given as

Therefore
F=81(343+3.05556)/343
F=81.721Hz
In conclusion, the frequency is
F=81.721Hz
Read more about frequency
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Answer:
The neutrinos are produced in the core of the sun by nuclear fusion and measuring their number helps us confirm that there are enough proton-proton chain reactions of each which produce a neutrino and going on in the Sun's core to explain the energy output of the Sun.
You have to upload this in the area of mathematicians..!