Specific Gravity and Pressure in Flowing Pipe

In summary, the question asks about the effect of passing a different ideal fluid with a specific gravity of 2.0 through a pipe that already has an ideal fluid with a specific gravity of 1.0 passing through it. The question asks if the pressure at any point in the pipe would decrease, remain the same, or increase by a factor of 2. Based on Bernoulli's equation, it is unclear how the pressure would be affected without knowing more information about the starting and finishing conditions. The given answer is that the pressure would increase by a factor of 2, but this cannot be determined without more information.
  • #1
Maneuver1
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Homework Statement

The following question is from ExamKrackers Physics [an MCAT prep book].

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An ideal fluid with specific gravity of 1.0 is passed through a pipe. Along the length of the pipe shown above are attached 3 vertical pipes which are sealed off as shown above. If now a different ideal fluid with a specific gravity of 2.0 is passed through the pipe at the same volume flow rate the pressure at any point in the pipe would:

a. decrease by a factor of 2
b. remain the same
c. increase by a factor of 2
d. more information is required

Homework Equations



K = P + pgy + 1/2*pv^2

The Attempt at a Solution



Based on bernoulli's equation above if you increase rho, pressure would have to decrease since the terms of bernoulli's equation sum to a constant. The answer given by Examkracers is that [c] the pressure increases by a factor of 2. I can't seem to see why this would be true. Any help would be greatly appreciated.
 
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  • #2
Welcome to PF!

Hi Maneuver1! Welcome to PF! :smile:

(have a rho: ρ and try using the X2 tag just above the Reply box :wink:)
Maneuver1 said:
Based on bernoulli's equation above if you increase rho, pressure would have to decrease since the terms of bernoulli's equation sum to a constant. The answer given by Examkracers is that [c] the pressure increases by a factor of 2.

I think you're both wrong …

Bernoulli's equation is constant along a streamline

unless you know something about the starting (or finishing) conditions, I don't see how you can say anything about the pressure :confused:
 

FAQ: Specific Gravity and Pressure in Flowing Pipe

What is specific gravity?

Specific gravity is a measure of the relative density of a substance compared to water. It is typically represented by the symbol "SG" and has no units.

How is specific gravity related to pressure in flowing pipes?

Specific gravity is one of the factors that affects the pressure in a flowing pipe. The higher the specific gravity of a fluid, the greater its weight and therefore the higher the pressure it exerts on the walls of the pipe.

What is the formula for calculating specific gravity?

The formula for calculating specific gravity is SG = ρ/ρwater, where ρ represents the density of the substance and ρwater represents the density of water.

What is the significance of specific gravity in fluid mechanics?

Specific gravity is an important parameter in fluid mechanics as it helps determine the buoyancy, flow rates, and pressure of fluids. It is also used in the design and operation of various systems, such as pipelines and storage tanks.

How does specific gravity affect the flow of fluids in a pipe?

The specific gravity of a fluid can affect its flow rate and pressure in a pipe. A higher specific gravity will result in a greater pressure and slower flow, while a lower specific gravity will result in a lower pressure and faster flow. This is due to the difference in weight and the resistance of the fluid to flow in the pipe.

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