A person watches an ambulance drive by them while emitting a steady sound from its siren. When the ambulance passes the person (switching from moving towards him to moving away from him), the perceived frequency of the sound he receives decreases by 11.2 percent. How fast is the ambulance driving

21.7 m/s

Explanation:

Let the velocity of ambulance is v and f is the real frequency of siren of ambulance.

the velocity of sound is 343 m/s

use the formula of Doppler's effect

   .... (1)

where, f' is the frequency of at the first time.

Now the source is moving away from the person, the frequency is given by

   .... (2)

According to the question,

f'' = f' - 11.0 % of f'

f'' = 0.881 f'

By equation (1) and (2)

40.817 = 1.881 v

v = 21.7 m/s

Thus, the speed of ambulance is 21.7 m/s.

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.  

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