Through which medium sound travels faster, iron or water? Give reason.

Can sound travel through vacuum?

What is meant by supersonic speed?

You and your friend are on the moon. Will you be able to hear any sound produced by your friend?

A stone is dropped from the top of a tower 750 m high into a pond of water at the base of the tower. Calculate the number of seconds for the splash to be heard?
(Given g = 10 m s^–2 and speed of sound = 340 m s^–1)