What is meant by the 'time-period' of a vibrating object? State its unit.

What are the usual causes of the partial hearing loss suffered by a person?

How can you show that sound cannot travel through a vacuum? Draw a labelled diagram of the apparatus used.

Define 'frequency' of a vibrating object. Name the unit in which frequency is measured.

A pendulum oscillates 40 times in 4 seconds. Calculate its

(i) time-period, and

(ii) frequency.

Can we hear the sound produced by the oscillations of this pendulum? Give reason for your answer.