Question

The table shows the speed of sound in fresh water and salt water.

Type of Water Speed (m/s)
salt water 1500
fresh water 1435

Which statement best describes why sound waves travel faster in salt water than in fresh water?
A.
Salt water exists in a different phase than fresh water.


B.
Fresh water is less dense than salt water.


C.
Salt water is hotter than fresh water.


D.
Fresh water has greater elasticity than salt water.

Answer 1

The correct answer is:

**B. Fresh water is less dense than salt water.**

While one might think that density leads to slower sound speeds, in this context, it is important to note that sound travels faster in more dense media if elasticity is comparable. However, in most practical situations, it's the combined effects of density and the bulk modulus (elasticity) that determines sound speed. In general, salt water's higher density, combined with its higher bulk modulus compared to fresh water, allows sound to travel faster in it.

Thus, B accurately conveys that fresh water's lower density contributes to its slower sound speed, but it's also worth understanding that the elasticity plays a crucial role, too. None of the other options accurately describe the relationship in context.