Specific volume and density problem

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The discussion focuses on solving a specific volume and density problem involving a pressure vessel containing liquid water and steam. For part A, the density of liquid water is calculated using the formula ρ = m/V, resulting in 50 kg/m³ based on the given volume and mass. Part B involves determining the mass of the steam using its specific volume, while part C requires calculating the overall density of the system by combining the masses of water and steam with the total volume. Participants confirm the correctness of the proposed methods for each part of the problem. The conversation highlights the importance of clear assumptions in solving fluid mechanics problems.
Xyius
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1. A pressure vessel of volume 100 liters is filled with 1 kg of liquid water and 80 liters of steam with a specific volume of 0.02 m3/kg. Determine
a. The density of the liquid water in SI fundamental units
b. The mass of the steam in grams
c. The density and the specific volume of the system (liquid water + steam)

Homework Equations


Specific\ Volume = \nu = \frac{1}{\rho} = \frac{V}{m}

The Attempt at a Solution


Basically, I am unsure about the assumptions that should be made for part A only. The vessel is 100 L and is filled with 1 kg of liquid water and 80L of steam. Is it correct of me to assume that the entire vessel is filled? So therefore.. (Since 20L = 0.02 cubic meters)
\rho_{water} = \frac{m}{V} = \frac{1kg}{0.02m^3} = 50\frac{kg}{m^3}

Does this sound right to you guys? Part B would be solved in a similar manner using the specific volume of steam that is given, and part C I am assuming you would do something like this..
\rho_{system} = \frac{m_{water + steam}}{V_{system}}
 
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Xyius said:

The Attempt at a Solution


Basically, I am unsure about the assumptions that should be made for part A only. The vessel is 100 L and is filled with 1 kg of liquid water and 80L of steam. Is it correct of me to assume that the entire vessel is filled? So therefore.. (Since 20L = 0.02 cubic meters)
\rho_{water} = \frac{m}{V} = \frac{1kg}{0.02m^3} = 50\frac{kg}{m^3}

Does this sound right to you guys?

Yep that would be correct.

Xyius said:
Part B would be solved in a similar manner using the specific volume of steam that is given, and part C I am assuming you would do something like this..
\rho_{system} = \frac{m_{water + steam}}{V_{system}}

part b would just be modifying your formula to get mass.

part c, that is correct as well (your method that is)
 
Cool thanks :)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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