**Answer:**

12.64968 Hz

**Explanation:**

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.

The object will continue moving in a straight line at constant speed.

The answer would be 70. I got my answer from www.iun.edu