The speed of sound in water is 1498 m/s. A sonar signal is sent straight down from a ship at a point just below the water surface, and 1.95 s later, the reflected signal is detected. How deep is the water?

Answer 1

Speed of sound = 1498 m/s
The sound takes 1.95 s to travel from the boat to the bottom and back. Half of this time is how long it takes to reach the bottom.

So 1.95s/2 = time to travel from boat to the bottom. velocity = distance / time.
since you now know time and velocity you can plug in and solve for distance.
Good luck =)