Question

Bells are made of metal and not of wood because

• A. Metals are elastic than wood
• B. The density of the metal is greater than that of wood
• C. The sound is not conducted by metals but is radiated
• D. Wood dampens vibrations faster

Answer 1

Answer: (A), (D)

Wood dampens vibrations faster
Metals are elastic than wood

There is a common misconception about elasticity. Many people think that if a material is elastic means it can be deformed easily. They believe that flexiblity and elasticity are the same. But that is not true.

Elasticity means the tendency of a material to restore its original form after the removal of the deforming forces.

Greater elasticity means greater restoring force and thus greater force is required to deform the material.

Wood restores itself only if the deformation is very little. If a greater deforming force is applied, then wood breaks.

If a wooden bell is struck harder to produce louder sound, then there is a possiblity that the bell will break.

Metals on the other had can retore themselves even after a comparatively greater deformation. Metals can sustain greater deformation as compared to wood. Thus, metals are more elastic than wood.

Louder sound can be made by a metal bell without damaging it.

We know that sound is produced due to vibration. The process by which the amplitude of vibration goes on decreasing and finally the vibration stops is known as damping.

If you strike a metal plate and a wooden surface to produce sound, then you'll notice that the sound due to the metal lasts for a longer time than the wood.

This shows that wood dampens vibrations faster than metal.

A metal bell can produce sound for a longer duration as compared to a wooden one.