Explain why a compound is classified as as substance

Awoman stands a distance d from a loud motor that emits sound uniformly in all directions. the sound intensity at her position is an uncomfortable 2.0×10-3 w/m2. at a distance 2.6 times as far from the motor, what are (a) the sound intensity and (b) the sound intensity level relative to the threshold of hearing?

True or false: the cycle of seasons on the earth is caused by the tilt of the earth on its axis toward and away from the sun.

The law of the conservation of momentum says that the total momentum of any closed and isolated system cannot