If the ultrasonic signal sent by the ship’s sonar was received after 3 seconds

If the ultrasonic signal sent by the ship’s sonar was received after 3 seconds (the speed of sound in the water is 1500 m / s), then the obstacle is at a distance

Given:

t = 3 seconds – the time after which the ultrasonic signal sent by the ship’s sonar returned back;

u = 1500 m / s (meters per second) – the speed of sound propagation in water.

It is required to determine l (meter) – the distance to the obstacle.

According to the condition of the problem, the signal sent by the ship reflected from the obstacle and returned back, that is, it covered the total distance equal to 2 * l. Then, to determine the distance, you must use the following formula:

2 * l = u * t;

l = u * t / 2 = 1500 * 3/2 = 4500/2 = 2250 meters (2.25 kilometers).

Answer: the distance to the obstacle is 2250 meters (2.25 kilometers).