Asailor strikes the side of his ship just below the surface of the sea. he hears the echo of the wave reflected from the ocean floor directly below 5.0 s later. how deep is the ocean at this point

3750 m

Explanation:

1) You can find in the literature or internet that the speed of sound in the ocean is about 1500 m/s.

2) Then, you can find the distance travel by the sound wave in 5.0s with the equation distance = speed × time

⇒ distance = 1500m/s × 5.0 s = 7500 m

3) That sound went down until the ocean floor below and cameback all the way until the sailor heard it.

Then, the deep of the ocean fllor is half that distance:

deep = 7500m / 2 = 3750m

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate