Question

Which of the following materials will reflect sound better?
(A) Cork
(B) Carpets
(C) Curtains made of cloth
(D) Steel

Answer 1

Hint
Sound is a longitudinal wave such that it causes air to compress and expand in the same direction while moving along. Sound particles vibrate in material, whether it is a gas, liquid, or solid, thereby losing some of its kinetic energy while moving further.

Complete step by step answer
The reflection of sound depends upon the following factors:
(i) Frequency
(ii) Wavelength.
The speed of sound waves is much more in solid medium and very low in gaseous. Thus, it can be said that sound waves move with a great speed in solids in comparison to liquids and gases due to the dense state of solids. Sound waves travel fastest in a vacuum medium.
But in the given question, it also depends upon the speed of sound. The speed of sound depends on some factors regarding the traveling medium namely, elasticity and density. The speed of sound waves traveling through a medium is faster when the elasticity of the medium is large. However, the speed of sound waves traveling through a medium is faster when the density of the medium is lesser. Mathematically, this relation between speed and these factors of the medium is expressed as,
${\rm{Speed}} = \dfrac{{{\rm{Elasticity}}}}{{{\rm{Density}}}}$
Since the elasticity of steel is more in comparison to any other material, the speed of sound waves traveling through it will me more
Therefore, (D) Steel is the required solution.

Additional information
The speed of sound also depends on the temperature but most important is its elasticity and density.

Note
The speed of sound of various materials are:
(i) Air 330m/s
(ii) Aluminium 5000m/s
(iii) Steel, mild 5920m/s
(iv) Steel, stainless 5800m/s