Question

A mother hawk screeches as she dives at you. You recall from biology that female hawks screech at 785 Hz , but you hear the screech at 890 Hz . How fast is the hawk approaching?

Answer 1

Answer:

Speed of the hawk, v = 40.4 m/s

Explanation:

It is given that,

Exact frequency of the female, f = 785 Hz

Observed frequency of female, f' = 890 Hz

Speed of sound, v = 343 m/s

Let v' is the speed of the hawk. It is based on the concept of Doppler's effect. We know that when the object approaches you, its speed is given by :

$f'=f(\dfrac{v}{v-v'})$

$890=785\times (\dfrac{343}{343-v'})$

v' = 40.4 m/s

So, the speed of the hawk is 40.4 m/s. Hence, this is the required solution.