Question

An observer puts ear on a railway line 500m from a friend with a hammer . When his friend hits the railway line with the hammer, the observer hears two sounds. The sound is first heard through:

Answer 1

Echo. This is so because it is the sound caused by the repeated reflection of sound waves and in this case this phenomenon takes place

Answer 2

:

The sound is firstly heard through the track because the sound travels faster in the solids than in gases.

Explanation:

The speed of sound depends upon the elasticity of the material and the density of  the material.

The speed of sound through a matter is given :

$v=\sqrt{\frac{E}{\rho} }$

where:

E= elasticity of the matter

$\rho =$ density of the matter

We know that elasticity is the property of a matter to regain its shape and size upon removal of the external deforming force. The maximum force a matter can withstand against without undergoing a permanent deformation the higher is its elasticity.

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TOPIC: speed of sound

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