13. A burglar alarm is wailing with a frequency of 1200. hertz. What
frequency does a cop hear who is driving towards the alarm at a speed of
40.0 m/s? The air temperature is 35.0 oC.

Frequency heard by the police is 1336 Hz

Explanation:

As we know that the speed of sound in air is given as

now we know that

t = 35 degree C

so we have

now we know that if source and observer moves relative to each other then the observed frequency by the observer is given as

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day