................ attached to the vocal cords can make the cords tight or loose.

The matter or substance through which sound is transmitted is called ................

Sound cannot travel in ..............

Sound is produced by to and fro motion of an object is known as .................

The maximum displacement associated with the particle constituting a wave is called ..............

............. is produced by vibration of the objects.

Properties of plastics

These fibres are obtained from natural sources.

............... is made of many repeating units.

....................is made by mixing of two types of fibres terylene and cotton.

It is also called as artificial wool or synthetic wool.

Are synthetic fibres stronger than natural fibres?