Question

State whether given statement is true or false:
Sound travels faster in vacuum than in air.
A. True
B. False

Answer 1

Hint: Recall that sound is a wave, to be more specific, a mechanical wave. Mechanical waves by their very definition transfers energy using inter particle interaction. In other words, we could say that sound waves require a medium for propagation, that is, cannot travel through mediums that are void of particles.

Complete step by step answer:
You may be familiar with the fact that the sound is a wave. Wave is a propagating disturbance caused due to various reasons transporting energy from one position to another. There are many classifications of waves.
Let us consider a slinky wave. When a disturbance is created at the first coil of a slinky, it further creates a push and pull on the second coil. As a result, the second coil is disturbed and gets displaced from its equilibrium position. The third coil of the slinky gets disturbed and also gets displaced from its equilibrium position and further creates push and pull on the fourth coil. You should understand that each individual particle takes part in this process by displacing the adjacent particle. Though, the energy was introduced on the first coil it is transferred along the medium from one coil to another.
This movement of slinky waves is analogous to that of a sound wave. Just like slinky wave sound waves require a medium for propagation (interconnected or interconnecting particles), an original source that creates this whole disturbance, also particle to particle interaction results in sound wave propagation. Just like the case of slinky in which each coil causes the neighboring coil to get displaced from its equilibrium position, in the sound wave each particle in the medium of propagation disturbs the neighboring particle and displaces it and thus the disturbance propagates throughout the medium. Since the sound wave requires a medium for the transportation of disturbance through particle-particle interaction we categorize sound waves under mechanical waves.
As a summary of the above explanation we could say that sound waves definitely require a medium for its propagation. In vacuum since there is no medium and hence no interconnected and interacting particles the propagation of sound is impossible. Which further proves that the above given statement in the question is false.

So, the correct answer is “Option B”.

Note: You could think of the demonstration done using a bell jar. The jar is first evacuated of air and then a ringing bell is placed inside it. If the given jar is made of glass, you could see the bell striking but will not be able to hear the sound. This happens because the jar is in vacuum and hence lacks particles for propagation of the sound produced. Or simply we could say that the sound wave doesn’t propagate through vacuum.