If a sound pulse is sent vertically downward into the sea and its reflected echo from the seafloor returns 6 seconds later, the depth of the water is meters. (The average speed of sound in seawater is 1500 m/sec.)

4500 metres

Explanation:

Echo is a reflection of sound wave. It is the sound heard after it has been reflected off the surface of a wall or cliff.

Time = 6 seconds

Speed of sound in water = 1500m/s

distance =?

From the relationship ;

Speed = distance / time

Distance = speed * time

Distance = 1500 * 6 = 9000 metres

Distance here represents the total distance traveled by the pulse that is distance to the seafloor and back to the surface.

Therefore the depth of the water is given by;

Depth = distance / 2

Depth = 9000 / 2 = 4500metres.

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.