Question

A bell is rung. What best describes the density of air around the bell?

a.  The air density does not change.

b.  The air density increases and then returns to normal levels.

c.  The air density decreases and then returns to normal levels.

d.  The air density increases and decreases repeatedly before returning to normal.

Answer 1

d. The air density increases and decreases repeatedly before returning to normal.

Step-by-step explanation:

when sound wave travel in the air then the air molecules will move to and fro about their mean position due to which sound energy propagate into the medium.

Due to this propagation of sound through the medium the pressure in the medium will go increasing and decreasing in form of rarefaction and compression and given as

`P = BAK sin(\omega t + kx + \phi)`

so here since pressure is changing from maximum to minimum so here density of medium also changes. So correct answer will be

d. The air density increases and decreases repeatedly before returning to normal.

Answer 2

D. The air density increases and decreases repeatedly before returning to normal. At rest, before the bell is rung, the density of the air is fairly undisturbed. Once the bell is rung, oscillating sound waves will cause the surrounding air to compress and expand due to the wave crests and troughs generated by the sound. This will result in a variety of destructive and constructive interference events. Eventually, the energy generated from the bell will be lost to the environment and the sound will subside as the sound waves become smaller and enough destructive interference has occurred.