Answer:
f=896Hz
Explanation:
Given data
Vs(speed of the ambulance)={(104 km/h)*(1000m*(1 h/3600)}=28.9m/s
f(frequency of the ambulance siren)=821 Hz
v(speed of sound)=345 m/s
Vo(speed of the observer)=0 m/s
To find
f(The ambulance is approaching the person)
Solution
From Doppler effect

As the ambulance approaches the we assign a positive sign for speed "vs" of the ambulance
So

Substitute the values from given data

Answer:
The colour of visible light depends on its wavelength. These wavelengths range from 700 nm at the red end of the spectrum to 400 nm at the violet end. Visible light waves are the only electromagnetic waves we can
Explanation:
B, C, and D.
Solar energy is green energy, it wouldn't contribute to global warming. However some places of the world don't receive as much sunlight (the poles) and at night you don't receive as much sunlight either. Solar energy is also very expensive to farm.
C.) ultraviolet
Ultraviolet because it is the most harmful of them all. Just like the x-rays, amirite?