Question

Give scientifcic reasons:
a. It is essential to change the tension on the vocal cords, as we produce different sound notes from our larynx.
b. Astronauts on the moon can not hear each other directly.
c. As the sound wave propagates from one place to the other in air, the air itself is not required to move from one place to the other.

Answer 1

a. Different sound is produced when frequency of vibration of the source of sound is changed. In humans, vocal cords in larynx vibrate and produce sound. Now, the frequency of vibration of vocal cords is directly dependent on the tension produced on it. The higher the tension on the chords, the shriller will be the voice produced. So, we can say that it is essential to change the tension on the vocal cords to produce different sound notes from our larynx.

b. Sound requires medium to travel. The absence of atmosphere on the Moon makes it medium less. Thus, the astronauts on the Moon cannot hear each other directly because of absence of the medium.

c. A vibrating object disturbs the air particles near it. The air particles get compressed as well as start vibrating and gain energy. These particles, vibrating about their mean position, then transfer their energy to the other layer of particles near to them. In this way, region of compression and rarefaction are created and hence sound is produced. So, in sound production, only the transfer of energy of the vibrating particles takes place and not the transfer of particles themselves. So, yes we can say that as the sound wave propagates from one place to the other in air, the air itself is not required to move from one place to the other.