Arrange the speeds of sound in the following media in ascending order at room temperature: air, water, iron.

Correct answer: (b) Air < Water < Iron

Explanation

Sound is a mechanical wave, and it travels faster in media that are more elastic (stiffer):

• air (gas): about 343 m/s;
• water (liquid): about 1,480 m/s;
• iron (solid): about 5,000 m/s or more.

So the ascending order is air < water < iron. In general, sound travels slowest in gases, faster in liquids and fastest in solids.