The frequency of the siren of an ambulance is 900 Hz and is approaching you. You are standing on a corner and observe a frequency of 960 Hz. What is the speed of the ambulance (in mph) if the speed of sound is v

= 47.53 mph

Explanation:

by using Doppler  Effect

the frequency f' is the observed frequency by the observer :

by using relations

where v is speed of sound in medium and is speed of source ( ambulance)

on  solving above equation we get

substitute the values we get

the answer is b

explanation:

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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