Assignment based on sound

1. A wave vibrates up and down two times in 0.4s and it covers a distance of 4m during this interval.calculate: a)frequency  b)Time period of the wave by drawing suitable graph.
2. Draw a suitable graph of a wave.Mark on it the amplitude of wave and wavelength of wave.
3. What do you mean by the characteristics of sound?
4. Roaring lion & buzzing mosquito both produces sound.which sound will travel faster? Justify your answer.
5. Why is the sound produced in air, not heard by a person deep inside the water?
6. Why is it possible to detect the approaching of a distant train by placing the ear very close to the railway line?
7. What type of hearing aids are required to the astronauts on the moon and why?
8. If a  person strikes at the the one end of a long iron tube and the listener places his ear at a very far distance on the other end.He hears the sound of striking two times,why?
9. Why can we not hear each other on the moon?
10. Explain, why a distant lightning flash is seen before the thunder is heard.
11. If a person sets his watch by the sound of a distant siren at 8.00 AM , will it go fast or slow and why?
12. Draw a sketch of the variation of the displacement with time for a sinusoidal wave motion and mark amplitude, wavelength, time period on it.
13. Distinguish between two musical sounds produced by two different instrument of equally loud & of same pitch.Draw a suitable graph showing notes.