Imagine that the tank is filled with water. the height of the liquid collin is 7 m and the area is 1.5 m² what’s the force of gravity acting on the column of water

== The volume of water in the tank is (1.5 m²) x (7 m) = 10.5 m³ .

== The density of water is 1000 kg / m³ .

== The mass of water in the tank is (10.5 m³) x (1000 kg/m³) = 10,500 kg.

== The force of gravity is (mass?) x (gravity)

force = (10,500 kg) x (9.8 m/s²)

force =  102,900 Newtons

sonar - device which is used to find the submit submarines, sankalp ship. sonar waves consists of a transmitter and detector which are installed in the observation centre on board of a ship. the ultrasonic waves are sent into the sea at high frequency about 1000 khz in all direction.

that would be b i just took the test : )