Identify the part which vibrates to produce sound in the following instruments.

(a) Dholak (b) Sitar (c) Flute

A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?

What is the difference between noise and music? Can music become noise sometimes?

List sources of noise pollution in your surroundings.