v = Velocity of sound in seawater = 1522 m/s
u = Velocity of dolphin = 7.2 m/s
f' = Actual frequency = 2674 Hz
From Doppler effect we get the relation
The frequency that will be received is 2661.35032 Hz
The difference in the frequency will be
it should be A. 2 m/s² because the equation for acceleration is ( final− initial) / Time so you must subtract 10 from 40 and you'll get 30 then you divide by 15 to get your answer 2.