Specific Gravity and Pressure in Flowing Pipe

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Maneuver1
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Homework Statement

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

Red hand-drawn sketch of a horizontal pipe running left to right with three vertical sealed tubes rising from it, one on the left, one in the middle and one on the right.


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.
 
Last edited:
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: