Question

Give scientific reason:
Astronauts on the moon cannot hear each other directly.

Answer 1

Hint: Recall the type of sound wave. Use the concept of transfer of the longitudinal wave from one place to the other. Also recall the condition for the transfer of a longitudinal wave.

Complete step by step answer:
The sound from one place is transferred to the other place in the form of a wave called sound wave.
The sound waves are the longitudinal waves.
Longitudinal waves require a medium for their transfer from one place to the other place.
When the sound is produced, the vibration of the source transfers the energy of the source to the adjacent particles in the medium.
In such a way, the sound is transferred from one place to the other place.
But on the moon, there is no atmosphere present. Hence, there is no medium and particles in the medium for the transfer of the sound wave.
Therefore, if one astronaut speaks something to the other astronaut, there are no medium particles to transfer the sound wave to the other astronaut.
As a result, the other astronaut cannot hear directly anything from the speaker astronaut.

So, the correct answer is “Option A”.

Additional Information:
The sound wave cannot travel on the moon because of the absence of the air. But the radio waves can travel through space very easily.
Hence, the astronauts use transmitters which transform sound waves into radio waves.
The sound from the speaker astronaut is converted into radio waves and when these radio waves reach another astronaut, they are again converted into sound waves.

Note:
The astronauts use transmitters on the moon to speak as they cannot hear sound from each other.
The particles of the medium vibrate in a direction parallel to the direction of propagation of the sound wave.