A pulse of sound is produced at the bottom of the boat the sound travels through the water and is reflected from the sea bed the sound then reaches the boat again after 1.2 seconds the speed of sound in the water is 1500 m/s how far below the bottom of the boat is the sea bed

none, its a machine

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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