Question

Bells are made of metal and not of wood because
A. The thermal conductivity of metal is greater than that of wood
B. The density of the metal is greater than that of wood
C. The sound is not conducted by wood and metals are elastic
D. Wood dampens vibrations while metals are elastic

Answer 1

Hint: You can start by explaining how metals are sonorous (material that makes a ringing sound on being struck) and woods are not sonorous. Also, all objects vibrate when they are struck, metals can sustain these vibrations for longer, whereas wood cannot sustain these vibrations for long and hence dampens the vibrations.

Complete answer:
Bells are made of metals and not of woods because of two reasons which we will discuss below.
For starters, the materials used to make the bell should be sonorous. A material is called sonorous when it is capable of producing a ringing of sound. Metals are generally sonorous, you must have heard the sound of two metal objects or parts colliding in your day to day life. Whereas, wood is not sonorous and does not produce a ringing sound when struck.
The second reason why the bells are not made of wood and are made of metal because when a bell made of metal is struck the particles that make up the bell start to vibrate, metals can sustain these vibrations for a longer duration leading to the ringing sound. Since, vibrations mean that the particles are going back and forth around a fixed position, due to this behavior we can also say that metals have elastic properties (because elastic materials can also return to their original position after being displaced from it). The particles of a wooden bell when struck also vibrate but wood is not able to sustain these vibrations for longer durations and the vibrations quickly dampen.
The bells are made out of metal and not wood because metals are sonorous, have elastic-like properties, and can sustain vibrations for longer durations than wood.

So, the correct answer is “Option D”.

Note:
We discussed in the solution above that metals are more suitable for making bells than wood because metals have some elastic like-behavior. So, why do we not use rubber to make bells, this is because rubber has elastic properties but it is so elastic that it absorbs any impact that it suffers on being stricken and does produce a ringing sound.