Why would the velocity of a mechanical wave change as it passes through each of the three states of matter (solids, liquids, and gasses)?

Because Mechanical waves move more quickly through solids than through liquid and through gases.

Explanation:

Of the three phases of matter (gas, liquid, and solid), sound waves as mechanical waves travel the slowest through gases, faster through liquids, and fastest through solids.

Sound moves slowest through a gas because the molecules in a gas are spaced very far apart. In order for sound to travel through air, the floating molecules of matter must vibrate and collide to form compression waves. Because the molecules of matter in a gas are spaced far apart, sound moves slowest through a gas.

Sound travels faster in liquids than in gases because molecules are packed more closely together. This means that when the liquid molecules begin to vibrate, they quickly begin to collide with each other forming a rapidly moving compression wave. Sound travels over four times faster than in air!

Sound travels fastest through solids. This is because molecules in a solid are packed against each other. When a vibration begins, the molecules of a solid immediately collide and the compression wave travels rapidly. Sound waves travel over 17 times faster through metals than through air.

3.2x10^7

thermal energy is the answer