TBR Gases Question Passage III

[ajumobim]

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If fresh water were used rather salt water, how would the results be affected?

Answer: The change in volume of the ball would be greater when submerged in salt water than fresh water, because salt water is denser than fresh water. Explanation: As the ball is submerged below the surface, the pressure exerted by the less massive fresh water is less than the pressure exerted by the more massive salt water. The greater the pressure, the more the volume decreases, so salt water reduces the volume of the ball more than fresh water.

The explanation makes sense, but while I was going through the passage, I had the following reasoning: Salt water is more dense, and thus less compressible than fresh water, so it would have a greater reduction in volume than salt water.

 

[azor ahai]

You should be treating fluids as ideal fluids except when viscosity comes into play (like in blood). Ideal fluids are incompressible.

 

[erythrocyte666]

If fresh water were used rather salt water, how would the results be affected?

Answer: The change in volume of the ball would be greater when submerged in salt water than fresh water, because salt water is denser than fresh water. Explanation: As the ball is submerged below the surface, the pressure exerted by the less massive fresh water is less than the pressure exerted by the more massive salt water. The greater the pressure, the more the volume decreases, so salt water reduces the volume of the ball more than fresh water.

The explanation makes sense, but while I was going through the passage, I had the following reasoning: Salt water is more dense, and thus less compressible than fresh water, so it would have a greater reduction in volume than salt water.

I haven't looked at the passage, but this seems like a simple gage pressure question which is given by eqn: P = (rho)gh
as long as depth the ball is submerged is the same in both cases, salt water due to its greater density exerts greater pressure and compresses ball more